<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:47d2523f-30bd-4016-8508-f5356078f2a4,g:5c6c8553-d372-482d-ac82-8bf2f2c3efc3-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
  <link:roleRef roleURI="http://www.leonardodrs.com/role/ConsolidatedStatementsofCashFlows" xlink:type="simple" xlink:href="drs-20251231.xsd#ConsolidatedStatementsofCashFlows"/>
  <link:definitionLink xlink:role="http://www.leonardodrs.com/role/ConsolidatedStatementsofCashFlows" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_730b62e8-7b03-4928-b856-e02241eef456" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_d99777eb-2fe1-4a62-b0f0-e679e6af7771" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_730b62e8-7b03-4928-b856-e02241eef456" xlink:to="loc_us-gaap_StatementTable_d99777eb-2fe1-4a62-b0f0-e679e6af7771" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_371eea45-76ba-489b-a82e-77bc81f543b8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_d99777eb-2fe1-4a62-b0f0-e679e6af7771" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_371eea45-76ba-489b-a82e-77bc81f543b8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_371eea45-76ba-489b-a82e-77bc81f543b8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_371eea45-76ba-489b-a82e-77bc81f543b8" xlink:to="loc_us-gaap_RelatedPartyDomain_371eea45-76ba-489b-a82e-77bc81f543b8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_021425a4-167a-4e4d-967e-9cc7901cafdf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_371eea45-76ba-489b-a82e-77bc81f543b8" xlink:to="loc_us-gaap_RelatedPartyDomain_021425a4-167a-4e4d-967e-9cc7901cafdf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonrelatedPartyMember_93160ec1-a0ee-4b6e-a18d-a592d4394fb2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NonrelatedPartyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_021425a4-167a-4e4d-967e-9cc7901cafdf" xlink:to="loc_us-gaap_NonrelatedPartyMember_93160ec1-a0ee-4b6e-a18d-a592d4394fb2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyMember_8c040dc9-9b0e-4e9a-8525-de2fa7200848" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RelatedPartyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_021425a4-167a-4e4d-967e-9cc7901cafdf" xlink:to="loc_us-gaap_RelatedPartyMember_8c040dc9-9b0e-4e9a-8525-de2fa7200848" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_779bc439-b4e0-45e3-8ff5-0d4f4c1d8dcb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_730b62e8-7b03-4928-b856-e02241eef456" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_779bc439-b4e0-45e3-8ff5-0d4f4c1d8dcb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_7f78d269-bbd3-4d2d-b5b1-5a4e3e3575d7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_779bc439-b4e0-45e3-8ff5-0d4f4c1d8dcb" xlink:to="loc_us-gaap_NetIncomeLoss_7f78d269-bbd3-4d2d-b5b1-5a4e3e3575d7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_d0bb6013-59db-4ada-bdaa-bf5d1ca87d1e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_779bc439-b4e0-45e3-8ff5-0d4f4c1d8dcb" xlink:to="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_d0bb6013-59db-4ada-bdaa-bf5d1ca87d1e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepreciationDepletionAndAmortization_a3477365-b5b2-4606-985f-21ab44ef08ff" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DepreciationDepletionAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_d0bb6013-59db-4ada-bdaa-bf5d1ca87d1e" xlink:to="loc_us-gaap_DepreciationDepletionAndAmortization_a3477365-b5b2-4606-985f-21ab44ef08ff" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxExpenseBenefit_0efb3895-a1d7-41ad-bfca-a8abee890990" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredIncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_d0bb6013-59db-4ada-bdaa-bf5d1ca87d1e" xlink:to="loc_us-gaap_DeferredIncomeTaxExpenseBenefit_0efb3895-a1d7-41ad-bfca-a8abee890990" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensation_bbd43a15-af26-4f54-9f00-55c68d559fd1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_d0bb6013-59db-4ada-bdaa-bf5d1ca87d1e" xlink:to="loc_us-gaap_ShareBasedCompensation_bbd43a15-af26-4f54-9f00-55c68d559fd1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherOperatingActivitiesCashFlowStatement_b10c1d40-3001-4717-a7a9-b8306864549c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherOperatingActivitiesCashFlowStatement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_d0bb6013-59db-4ada-bdaa-bf5d1ca87d1e" xlink:to="loc_us-gaap_OtherOperatingActivitiesCashFlowStatement_b10c1d40-3001-4717-a7a9-b8306864549c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_e01695a6-79a1-46c7-bff7-7cfadd0701eb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInOperatingCapitalAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_d0bb6013-59db-4ada-bdaa-bf5d1ca87d1e" xlink:to="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_e01695a6-79a1-46c7-bff7-7cfadd0701eb" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsReceivable_1dc00308-067d-4b9d-989a-d4a268a934fb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInAccountsReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_e01695a6-79a1-46c7-bff7-7cfadd0701eb" xlink:to="loc_us-gaap_IncreaseDecreaseInAccountsReceivable_1dc00308-067d-4b9d-989a-d4a268a934fb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInContractWithCustomerAsset_4fba5186-7b15-4e8e-b37d-29961b0e7e77" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInContractWithCustomerAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_e01695a6-79a1-46c7-bff7-7cfadd0701eb" xlink:to="loc_us-gaap_IncreaseDecreaseInContractWithCustomerAsset_4fba5186-7b15-4e8e-b37d-29961b0e7e77" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInInventories_2ee988f7-68e9-48aa-b6d2-64108af30b07" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInInventories"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_e01695a6-79a1-46c7-bff7-7cfadd0701eb" xlink:to="loc_us-gaap_IncreaseDecreaseInInventories_2ee988f7-68e9-48aa-b6d2-64108af30b07" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInPrepaidExpense_cd6bd50b-8a26-4103-84ae-d1e85ac17248" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInPrepaidExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_e01695a6-79a1-46c7-bff7-7cfadd0701eb" xlink:to="loc_us-gaap_IncreaseDecreaseInPrepaidExpense_cd6bd50b-8a26-4103-84ae-d1e85ac17248" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInOtherCurrentAssets_bc73f13e-1fa4-4638-9566-937cd4793c6a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInOtherCurrentAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_e01695a6-79a1-46c7-bff7-7cfadd0701eb" xlink:to="loc_us-gaap_IncreaseDecreaseInOtherCurrentAssets_bc73f13e-1fa4-4638-9566-937cd4793c6a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInOtherNoncurrentAssets_446b23b5-4eeb-4516-bfaf-b5c31a974899" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInOtherNoncurrentAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_e01695a6-79a1-46c7-bff7-7cfadd0701eb" xlink:to="loc_us-gaap_IncreaseDecreaseInOtherNoncurrentAssets_446b23b5-4eeb-4516-bfaf-b5c31a974899" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInPensionAndPostretirementObligations_97e275c0-3936-4bf3-b0b1-5915abfe1fdd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInPensionAndPostretirementObligations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_e01695a6-79a1-46c7-bff7-7cfadd0701eb" xlink:to="loc_us-gaap_IncreaseDecreaseInPensionAndPostretirementObligations_97e275c0-3936-4bf3-b0b1-5915abfe1fdd" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsPayable_601b83ad-4e2c-4329-b551-649874f855f4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInAccountsPayable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_e01695a6-79a1-46c7-bff7-7cfadd0701eb" xlink:to="loc_us-gaap_IncreaseDecreaseInAccountsPayable_601b83ad-4e2c-4329-b551-649874f855f4" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInContractWithCustomerLiability_e32161e0-6698-47ad-b0e2-42a0c7bac64d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInContractWithCustomerLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_e01695a6-79a1-46c7-bff7-7cfadd0701eb" xlink:to="loc_us-gaap_IncreaseDecreaseInContractWithCustomerLiability_e32161e0-6698-47ad-b0e2-42a0c7bac64d" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInOtherCurrentLiabilities_f779f417-eb09-4d26-b28b-a43ba0e424b3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInOtherCurrentLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_e01695a6-79a1-46c7-bff7-7cfadd0701eb" xlink:to="loc_us-gaap_IncreaseDecreaseInOtherCurrentLiabilities_f779f417-eb09-4d26-b28b-a43ba0e424b3" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInOtherNoncurrentLiabilities_c67d7daf-c817-42ef-8835-68dcde1490e2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInOtherNoncurrentLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInOperatingCapitalAbstract_e01695a6-79a1-46c7-bff7-7cfadd0701eb" xlink:to="loc_us-gaap_IncreaseDecreaseInOtherNoncurrentLiabilities_c67d7daf-c817-42ef-8835-68dcde1490e2" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_51d4dcca-2297-4a13-8610-e677ddd3c42b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_779bc439-b4e0-45e3-8ff5-0d4f4c1d8dcb" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_51d4dcca-2297-4a13-8610-e677ddd3c42b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_7b4a85c6-07bf-40bd-be4b-96de206c5f29" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_730b62e8-7b03-4928-b856-e02241eef456" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_7b4a85c6-07bf-40bd-be4b-96de206c5f29" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_f2a996a0-67cf-4ed4-a2a7-ef63d98e7e8d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsToAcquirePropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_7b4a85c6-07bf-40bd-be4b-96de206c5f29" xlink:to="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_f2a996a0-67cf-4ed4-a2a7-ef63d98e7e8d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromSaleOfProductiveAssets_f8cd4bd9-301f-42b3-ae9d-86c9679778f8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProceedsFromSaleOfProductiveAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_7b4a85c6-07bf-40bd-be4b-96de206c5f29" xlink:to="loc_us-gaap_ProceedsFromSaleOfProductiveAssets_f8cd4bd9-301f-42b3-ae9d-86c9679778f8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForProceedsFromInvestments_7b6861ea-b245-4672-975f-92499c8d98c2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsForProceedsFromInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_7b4a85c6-07bf-40bd-be4b-96de206c5f29" xlink:to="loc_us-gaap_PaymentsForProceedsFromInvestments_7b6861ea-b245-4672-975f-92499c8d98c2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_7d84d7c4-431d-4d5f-846a-7bbf733be95c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_7b4a85c6-07bf-40bd-be4b-96de206c5f29" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_7d84d7c4-431d-4d5f-846a-7bbf733be95c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_e584947c-ec68-4337-b927-4e7d844f247f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_730b62e8-7b03-4928-b856-e02241eef456" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_e584947c-ec68-4337-b927-4e7d844f247f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromRepaymentsOfShortTermDebtMaturingInThreeMonthsOrLess_0a666d54-d7e7-40d2-9a0d-c93f6310700f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProceedsFromRepaymentsOfShortTermDebtMaturingInThreeMonthsOrLess"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_e584947c-ec68-4337-b927-4e7d844f247f" xlink:to="loc_us-gaap_ProceedsFromRepaymentsOfShortTermDebtMaturingInThreeMonthsOrLess_0a666d54-d7e7-40d2-9a0d-c93f6310700f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfLongTermLinesOfCredit_826386c3-d0b7-4a94-9dcc-94e60b86dc17" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RepaymentsOfLongTermLinesOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_e584947c-ec68-4337-b927-4e7d844f247f" xlink:to="loc_us-gaap_RepaymentsOfLongTermLinesOfCredit_826386c3-d0b7-4a94-9dcc-94e60b86dc17" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromLongTermLinesOfCredit_784567ce-bcd7-4620-8dd0-0016e629551e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProceedsFromLongTermLinesOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_e584947c-ec68-4337-b927-4e7d844f247f" xlink:to="loc_us-gaap_ProceedsFromLongTermLinesOfCredit_784567ce-bcd7-4620-8dd0-0016e629551e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_32838c10-7115-4788-948b-f54e1c097927" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProceedsFromIssuanceOfCommonStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_e584947c-ec68-4337-b927-4e7d844f247f" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_32838c10-7115-4788-948b-f54e1c097927" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForRepurchaseOfCommonStock_947f0ba6-08dd-4ccb-8745-6b767b2ef459" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsForRepurchaseOfCommonStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_e584947c-ec68-4337-b927-4e7d844f247f" xlink:to="loc_us-gaap_PaymentsForRepurchaseOfCommonStock_947f0ba6-08dd-4ccb-8745-6b767b2ef459" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_3c229fcb-de3e-42f9-b476-701a554f0f30" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_e584947c-ec68-4337-b927-4e7d844f247f" xlink:to="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_3c229fcb-de3e-42f9-b476-701a554f0f30" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfDividends_fd7d023b-e3a5-44e6-8482-0747134c1322" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsOfDividends"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_e584947c-ec68-4337-b927-4e7d844f247f" xlink:to="loc_us-gaap_PaymentsOfDividends_fd7d023b-e3a5-44e6-8482-0747134c1322" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromPaymentsForOtherFinancingActivities_ae42446d-0a7b-418a-ba8a-fd9b2960bbb4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProceedsFromPaymentsForOtherFinancingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_e584947c-ec68-4337-b927-4e7d844f247f" xlink:to="loc_us-gaap_ProceedsFromPaymentsForOtherFinancingActivities_ae42446d-0a7b-418a-ba8a-fd9b2960bbb4" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_b6b41760-0a23-4033-8a68-ff130542093c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_e584947c-ec68-4337-b927-4e7d844f247f" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_b6b41760-0a23-4033-8a68-ff130542093c" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_06f839ff-7065-4215-b2ab-f1b223c37495" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_730b62e8-7b03-4928-b856-e02241eef456" xlink:to="loc_us-gaap_EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_06f839ff-7065-4215-b2ab-f1b223c37495" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_085175c8-9c33-4e8d-9c3b-d4b4050a9051" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_730b62e8-7b03-4928-b856-e02241eef456" xlink:to="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_085175c8-9c33-4e8d-9c3b-d4b4050a9051" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_d1e18bcc-5335-4b6f-bd0c-23a3f19fdc82" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_730b62e8-7b03-4928-b856-e02241eef456" xlink:to="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_d1e18bcc-5335-4b6f-bd0c-23a3f19fdc82" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_8fbdedd0-8b9d-43d7-b4f3-b72ba11be7eb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.leonardodrs.com/role/ConsolidatedStatementsofStockholdersEquity" xlink:type="simple" xlink:href="drs-20251231.xsd#ConsolidatedStatementsofStockholdersEquity"/>
  <link:definitionLink xlink:role="http://www.leonardodrs.com/role/ConsolidatedStatementsofStockholdersEquity" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_985697af-8981-48df-bead-589c67b6ab4f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_69199f55-e195-49e2-bdc5-d5a2ec385d04" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_985697af-8981-48df-bead-589c67b6ab4f" xlink:to="loc_us-gaap_StatementTable_69199f55-e195-49e2-bdc5-d5a2ec385d04" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_cc4c1d57-1f4c-4d71-9717-4e5d31e1a720" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_69199f55-e195-49e2-bdc5-d5a2ec385d04" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_cc4c1d57-1f4c-4d71-9717-4e5d31e1a720" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_cc4c1d57-1f4c-4d71-9717-4e5d31e1a720_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_cc4c1d57-1f4c-4d71-9717-4e5d31e1a720" xlink:to="loc_us-gaap_EquityComponentDomain_cc4c1d57-1f4c-4d71-9717-4e5d31e1a720_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_0a9fcc3b-4449-4bc2-b081-542c11a4fc82" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_cc4c1d57-1f4c-4d71-9717-4e5d31e1a720" xlink:to="loc_us-gaap_EquityComponentDomain_0a9fcc3b-4449-4bc2-b081-542c11a4fc82" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_d08741ca-99c6-4c59-8f83-013b2fe207fb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_0a9fcc3b-4449-4bc2-b081-542c11a4fc82" xlink:to="loc_us-gaap_CommonStockMember_d08741ca-99c6-4c59-8f83-013b2fe207fb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_950376e6-aaf9-4cb3-8188-85c79f68616d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_0a9fcc3b-4449-4bc2-b081-542c11a4fc82" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_950376e6-aaf9-4cb3-8188-85c79f68616d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_53917cc7-e8e3-41c6-b4f5-57d0f576d372" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_0a9fcc3b-4449-4bc2-b081-542c11a4fc82" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_53917cc7-e8e3-41c6-b4f5-57d0f576d372" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_65efc661-f2f4-4a90-8e17-4fa8ed46d2ce" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_0a9fcc3b-4449-4bc2-b081-542c11a4fc82" xlink:to="loc_us-gaap_RetainedEarningsMember_65efc661-f2f4-4a90-8e17-4fa8ed46d2ce" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2ae1b966-3ae7-40b0-8dda-ba100db66385" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_985697af-8981-48df-bead-589c67b6ab4f" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2ae1b966-3ae7-40b0-8dda-ba100db66385" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_96c55f9c-d97b-4557-ad00-daa08608e38c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2ae1b966-3ae7-40b0-8dda-ba100db66385" xlink:to="loc_us-gaap_StockholdersEquity_96c55f9c-d97b-4557-ad00-daa08608e38c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComprehensiveIncomeNetOfTax_e593ced8-1bf1-40a6-b8a3-ffab9675d422" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ComprehensiveIncomeNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2ae1b966-3ae7-40b0-8dda-ba100db66385" xlink:to="loc_us-gaap_ComprehensiveIncomeNetOfTax_e593ced8-1bf1-40a6-b8a3-ffab9675d422" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_bc8757b4-9934-415d-be38-f9ca2261d393" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2ae1b966-3ae7-40b0-8dda-ba100db66385" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_bc8757b4-9934-415d-be38-f9ca2261d393" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_fd77c900-6a07-4c06-b76b-f02f2256a548" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodValueNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2ae1b966-3ae7-40b0-8dda-ba100db66385" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_fd77c900-6a07-4c06-b76b-f02f2256a548" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalDividendsInExcessOfRetainedEarnings_e96874b1-65a7-4622-829f-a5d1a061467d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalDividendsInExcessOfRetainedEarnings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2ae1b966-3ae7-40b0-8dda-ba100db66385" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalDividendsInExcessOfRetainedEarnings_e96874b1-65a7-4622-829f-a5d1a061467d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodValue_4d36f315-c22c-4626-b109-4e055ffb8bfa" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockRepurchasedAndRetiredDuringPeriodValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_2ae1b966-3ae7-40b0-8dda-ba100db66385" xlink:to="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodValue_4d36f315-c22c-4626-b109-4e055ffb8bfa" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_697672cf-e4c6-4409-aba4-2d531823c024" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquity"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.leonardodrs.com/role/SummaryofSignificantAccountingPoliciesConcentrationRiskDetails" xlink:type="simple" xlink:href="drs-20251231.xsd#SummaryofSignificantAccountingPoliciesConcentrationRiskDetails"/>
  <link:definitionLink xlink:role="http://www.leonardodrs.com/role/SummaryofSignificantAccountingPoliciesConcentrationRiskDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskLineItems_89c28fd5-ee75-4a5d-904a-801b34ce0fa8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTable_85cee3a7-c525-42e2-af1d-ef75f8ab7207" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_89c28fd5-ee75-4a5d-904a-801b34ce0fa8" xlink:to="loc_us-gaap_ConcentrationRiskTable_85cee3a7-c525-42e2-af1d-ef75f8ab7207" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis_8109e29f-9ff7-4616-b388-aa28c7bae540" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MajorCustomersAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_85cee3a7-c525-42e2-af1d-ef75f8ab7207" xlink:to="loc_srt_MajorCustomersAxis_8109e29f-9ff7-4616-b388-aa28c7bae540" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_8109e29f-9ff7-4616-b388-aa28c7bae540_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MajorCustomersAxis_8109e29f-9ff7-4616-b388-aa28c7bae540" xlink:to="loc_srt_NameOfMajorCustomerDomain_8109e29f-9ff7-4616-b388-aa28c7bae540_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_9997c40c-592e-48ee-8bd8-4d425b800bc3" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MajorCustomersAxis_8109e29f-9ff7-4616-b388-aa28c7bae540" xlink:to="loc_srt_NameOfMajorCustomerDomain_9997c40c-592e-48ee-8bd8-4d425b800bc3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_USDepartmentOfDefenseMember_4a54f272-c412-42bf-a531-e62c2ec96bd4" xlink:href="drs-20251231.xsd#drs_USDepartmentOfDefenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_9997c40c-592e-48ee-8bd8-4d425b800bc3" xlink:to="loc_drs_USDepartmentOfDefenseMember_4a54f272-c412-42bf-a531-e62c2ec96bd4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_InternationalAndCommercialCustomersMember_fe8da517-cf8d-417a-9d8c-2303143c40a3" xlink:href="drs-20251231.xsd#drs_InternationalAndCommercialCustomersMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_9997c40c-592e-48ee-8bd8-4d425b800bc3" xlink:to="loc_drs_InternationalAndCommercialCustomersMember_fe8da517-cf8d-417a-9d8c-2303143c40a3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_219e177a-a339-409c-b90c-0559217aaf33" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_85cee3a7-c525-42e2-af1d-ef75f8ab7207" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_219e177a-a339-409c-b90c-0559217aaf33" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_219e177a-a339-409c-b90c-0559217aaf33_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_219e177a-a339-409c-b90c-0559217aaf33" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_219e177a-a339-409c-b90c-0559217aaf33_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_2fcb1014-8a7c-4323-83cb-63e931340648" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_219e177a-a339-409c-b90c-0559217aaf33" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_2fcb1014-8a7c-4323-83cb-63e931340648" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerMember_eb851678-75b9-4504-9fea-b2d72c5dd985" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueFromContractWithCustomerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_2fcb1014-8a7c-4323-83cb-63e931340648" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerMember_eb851678-75b9-4504-9fea-b2d72c5dd985" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_d8cb7e0d-15db-4a68-a060-cc5f7775de93" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_85cee3a7-c525-42e2-af1d-ef75f8ab7207" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_d8cb7e0d-15db-4a68-a060-cc5f7775de93" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_d8cb7e0d-15db-4a68-a060-cc5f7775de93_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_d8cb7e0d-15db-4a68-a060-cc5f7775de93" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_d8cb7e0d-15db-4a68-a060-cc5f7775de93_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_d73c050a-1594-47c6-89ca-6185f437482b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_d8cb7e0d-15db-4a68-a060-cc5f7775de93" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_d73c050a-1594-47c6-89ca-6185f437482b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GovernmentContractsConcentrationRiskMember_cbf12799-c99e-4cf0-9a28-d9d343857024" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GovernmentContractsConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_d73c050a-1594-47c6-89ca-6185f437482b" xlink:to="loc_us-gaap_GovernmentContractsConcentrationRiskMember_cbf12799-c99e-4cf0-9a28-d9d343857024" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerConcentrationRiskMember_3e3e9b32-cfb1-41e5-802c-69087710f46f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CustomerConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_d73c050a-1594-47c6-89ca-6185f437482b" xlink:to="loc_us-gaap_CustomerConcentrationRiskMember_3e3e9b32-cfb1-41e5-802c-69087710f46f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfReportableSegments_3158eb60-0c24-40a4-879b-0feb495afa27" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NumberOfReportableSegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_89c28fd5-ee75-4a5d-904a-801b34ce0fa8" xlink:to="loc_us-gaap_NumberOfReportableSegments_3158eb60-0c24-40a4-879b-0feb495afa27" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_c962926a-23d3-4d83-b39f-54163e2effab" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskPercentage1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_89c28fd5-ee75-4a5d-904a-801b34ce0fa8" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_c962926a-23d3-4d83-b39f-54163e2effab" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.leonardodrs.com/role/SummaryofSignificantAccountingPoliciesPropertyPlantandEquipmentDetails" xlink:type="simple" xlink:href="drs-20251231.xsd#SummaryofSignificantAccountingPoliciesPropertyPlantandEquipmentDetails"/>
  <link:definitionLink xlink:role="http://www.leonardodrs.com/role/SummaryofSignificantAccountingPoliciesPropertyPlantandEquipmentDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_1eb25a17-f262-4e44-8100-467bef9c944f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_e7fb6b16-52eb-4365-9257-c59209c717d5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_1eb25a17-f262-4e44-8100-467bef9c944f" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_e7fb6b16-52eb-4365-9257-c59209c717d5" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_51fcbda1-96bd-4b84-a551-238c2fc6f2bb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_e7fb6b16-52eb-4365-9257-c59209c717d5" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_51fcbda1-96bd-4b84-a551-238c2fc6f2bb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_51fcbda1-96bd-4b84-a551-238c2fc6f2bb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_51fcbda1-96bd-4b84-a551-238c2fc6f2bb" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_51fcbda1-96bd-4b84-a551-238c2fc6f2bb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_94c277e9-f1af-4766-b8a8-17762649ca06" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_51fcbda1-96bd-4b84-a551-238c2fc6f2bb" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_94c277e9-f1af-4766-b8a8-17762649ca06" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MachineryAndEquipmentMember_a92ccfb5-65a8-4044-80b9-b6c3b8e02d97" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MachineryAndEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_94c277e9-f1af-4766-b8a8-17762649ca06" xlink:to="loc_us-gaap_MachineryAndEquipmentMember_a92ccfb5-65a8-4044-80b9-b6c3b8e02d97" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BuildingAndBuildingImprovementsMember_9c794d67-c1b9-4835-b2dd-b32a7a1c1928" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BuildingAndBuildingImprovementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_94c277e9-f1af-4766-b8a8-17762649ca06" xlink:to="loc_us-gaap_BuildingAndBuildingImprovementsMember_9c794d67-c1b9-4835-b2dd-b32a7a1c1928" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_5fddb6b6-2d5f-4ac4-90e7-23e4c62b80b4" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_e7fb6b16-52eb-4365-9257-c59209c717d5" xlink:to="loc_srt_RangeAxis_5fddb6b6-2d5f-4ac4-90e7-23e4c62b80b4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_5fddb6b6-2d5f-4ac4-90e7-23e4c62b80b4_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_5fddb6b6-2d5f-4ac4-90e7-23e4c62b80b4" xlink:to="loc_srt_RangeMember_5fddb6b6-2d5f-4ac4-90e7-23e4c62b80b4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_d29c149d-b8ce-487e-a3bc-d8c8bf12b5d6" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_5fddb6b6-2d5f-4ac4-90e7-23e4c62b80b4" xlink:to="loc_srt_RangeMember_d29c149d-b8ce-487e-a3bc-d8c8bf12b5d6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_8981e7ec-9511-427a-b841-dd9d5277a3b0" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_d29c149d-b8ce-487e-a3bc-d8c8bf12b5d6" xlink:to="loc_srt_MinimumMember_8981e7ec-9511-427a-b841-dd9d5277a3b0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_7b64949c-e9d8-430a-89fc-3826d13e4443" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_d29c149d-b8ce-487e-a3bc-d8c8bf12b5d6" xlink:to="loc_srt_MaximumMember_7b64949c-e9d8-430a-89fc-3826d13e4443" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_aa50e56b-8f88-4436-97d0-9a552ff90f76" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_1eb25a17-f262-4e44-8100-467bef9c944f" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_aa50e56b-8f88-4436-97d0-9a552ff90f76" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.leonardodrs.com/role/SummaryofSignificantAccountingPoliciesInvestmentsDetails" xlink:type="simple" xlink:href="drs-20251231.xsd#SummaryofSignificantAccountingPoliciesInvestmentsDetails"/>
  <link:definitionLink xlink:role="http://www.leonardodrs.com/role/SummaryofSignificantAccountingPoliciesInvestmentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionLineItems_019c21f4-7234-79d8-9c58-95abeb39b51d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RelatedPartyTransactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_019c21f4-7234-7589-a141-ee856b59fc00" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_019c21f4-7234-79d8-9c58-95abeb39b51d" xlink:to="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_019c21f4-7234-7589-a141-ee856b59fc00" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_019c21f4-7234-7296-9673-afd3a2beaf05" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_019c21f4-7234-7589-a141-ee856b59fc00" xlink:to="loc_srt_CounterpartyNameAxis_019c21f4-7234-7296-9673-afd3a2beaf05" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019c21f4-7234-7296-9673-afd3a2beaf05_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_019c21f4-7234-7296-9673-afd3a2beaf05" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019c21f4-7234-7296-9673-afd3a2beaf05_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019c21f4-7234-7dcc-b96d-72f7ab3690eb" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_019c21f4-7234-7296-9673-afd3a2beaf05" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019c21f4-7234-7dcc-b96d-72f7ab3690eb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_UnnamedPrivateCompanyMember_019c21f4-7234-7e5c-9ae6-9bcf62645ed8" xlink:href="drs-20251231.xsd#drs_UnnamedPrivateCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019c21f4-7234-7dcc-b96d-72f7ab3690eb" xlink:to="loc_drs_UnnamedPrivateCompanyMember_019c21f4-7234-7e5c-9ae6-9bcf62645ed8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019c21f4-7234-761e-a4a7-0fb1354cf5e3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_019c21f4-7234-7589-a141-ee856b59fc00" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019c21f4-7234-761e-a4a7-0fb1354cf5e3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_019c21f4-7234-761e-a4a7-0fb1354cf5e3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019c21f4-7234-761e-a4a7-0fb1354cf5e3" xlink:to="loc_us-gaap_RelatedPartyDomain_019c21f4-7234-761e-a4a7-0fb1354cf5e3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_019c21f4-7234-742d-a5f4-7b36c1a2812d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019c21f4-7234-761e-a4a7-0fb1354cf5e3" xlink:to="loc_us-gaap_RelatedPartyDomain_019c21f4-7234-742d-a5f4-7b36c1a2812d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyMember_019c21f4-7234-714c-a096-f72149e7f881" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RelatedPartyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_019c21f4-7234-742d-a5f4-7b36c1a2812d" xlink:to="loc_us-gaap_RelatedPartyMember_019c21f4-7234-714c-a096-f72149e7f881" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Investments_019c21f4-7234-7317-8a8a-3146f2e7e0e7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Investments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_019c21f4-7234-79d8-9c58-95abeb39b51d" xlink:to="loc_us-gaap_Investments_019c21f4-7234-7317-8a8a-3146f2e7e0e7" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.leonardodrs.com/role/RevenuefromContractswithCustomersEstimateatCompletionAdjustmentsDetails" xlink:type="simple" xlink:href="drs-20251231.xsd#RevenuefromContractswithCustomersEstimateatCompletionAdjustmentsDetails"/>
  <link:definitionLink xlink:role="http://www.leonardodrs.com/role/RevenuefromContractswithCustomersEstimateatCompletionAdjustmentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ChangeInAccountingEstimateLineItems_7785294f-744d-4476-b20f-1590486b4bb3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ChangeInAccountingEstimateLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfChangeInAccountingEstimateTable_dbdaed39-5b4b-439e-9d0b-be83a0515095" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfChangeInAccountingEstimateTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ChangeInAccountingEstimateLineItems_7785294f-744d-4476-b20f-1590486b4bb3" xlink:to="loc_us-gaap_ScheduleOfChangeInAccountingEstimateTable_dbdaed39-5b4b-439e-9d0b-be83a0515095" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ChangeInAccountingEstimateByTypeAxis_1ad0534e-021a-4ac3-9c1b-7cd96ae1880b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ChangeInAccountingEstimateByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfChangeInAccountingEstimateTable_dbdaed39-5b4b-439e-9d0b-be83a0515095" xlink:to="loc_us-gaap_ChangeInAccountingEstimateByTypeAxis_1ad0534e-021a-4ac3-9c1b-7cd96ae1880b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ChangeInAccountingEstimateTypeDomain_1ad0534e-021a-4ac3-9c1b-7cd96ae1880b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ChangeInAccountingEstimateTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ChangeInAccountingEstimateByTypeAxis_1ad0534e-021a-4ac3-9c1b-7cd96ae1880b" xlink:to="loc_us-gaap_ChangeInAccountingEstimateTypeDomain_1ad0534e-021a-4ac3-9c1b-7cd96ae1880b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ChangeInAccountingEstimateTypeDomain_5b26918a-1c3a-4aab-8f79-0fff2e0c1362" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ChangeInAccountingEstimateTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ChangeInAccountingEstimateByTypeAxis_1ad0534e-021a-4ac3-9c1b-7cd96ae1880b" xlink:to="loc_us-gaap_ChangeInAccountingEstimateTypeDomain_5b26918a-1c3a-4aab-8f79-0fff2e0c1362" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractsAccountedForUnderPercentageOfCompletionMember_273173ef-2e39-46d6-85d7-7661cbd5ad2e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ContractsAccountedForUnderPercentageOfCompletionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ChangeInAccountingEstimateTypeDomain_5b26918a-1c3a-4aab-8f79-0fff2e0c1362" xlink:to="loc_us-gaap_ContractsAccountedForUnderPercentageOfCompletionMember_273173ef-2e39-46d6-85d7-7661cbd5ad2e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_RevenueAndOperatingIncomeLoss_e6406088-804f-45e0-bd92-4c32f9eed136" xlink:href="drs-20251231.xsd#drs_RevenueAndOperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ChangeInAccountingEstimateLineItems_7785294f-744d-4476-b20f-1590486b4bb3" xlink:to="loc_drs_RevenueAndOperatingIncomeLoss_e6406088-804f-45e0-bd92-4c32f9eed136" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_RevenueFromContractWithCustomerExcludingAssessedTaxPercent_e7ef21d4-e909-45f0-978e-1ec8cc13fe74" xlink:href="drs-20251231.xsd#drs_RevenueFromContractWithCustomerExcludingAssessedTaxPercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ChangeInAccountingEstimateLineItems_7785294f-744d-4476-b20f-1590486b4bb3" xlink:to="loc_drs_RevenueFromContractWithCustomerExcludingAssessedTaxPercent_e7ef21d4-e909-45f0-978e-1ec8cc13fe74" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_f10511f1-8141-4770-9048-af234624fc49" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ChangeInAccountingEstimateLineItems_7785294f-744d-4476-b20f-1590486b4bb3" xlink:to="loc_us-gaap_NetIncomeLoss_f10511f1-8141-4770-9048-af234624fc49" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDiluted_da2a6c41-e7e2-4a1c-9a14-12df4b1b8c68" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EarningsPerShareDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ChangeInAccountingEstimateLineItems_7785294f-744d-4476-b20f-1590486b4bb3" xlink:to="loc_us-gaap_EarningsPerShareDiluted_da2a6c41-e7e2-4a1c-9a14-12df4b1b8c68" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.leonardodrs.com/role/RevenuefromContractswithCustomersRemainingPerformanceObligationsNarrativeDetails" xlink:type="simple" xlink:href="drs-20251231.xsd#RevenuefromContractswithCustomersRemainingPerformanceObligationsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.leonardodrs.com/role/RevenuefromContractswithCustomersRemainingPerformanceObligationsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_3d2d16e0-8046-4fec-8219-5db0f80e645b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_10661794-a54b-4056-85a2-7d7101605ad3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_3d2d16e0-8046-4fec-8219-5db0f80e645b" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_10661794-a54b-4056-85a2-7d7101605ad3" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_460b82e0-5b9c-4bb2-8e0f-a7c2c2a7534b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_10661794-a54b-4056-85a2-7d7101605ad3" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_460b82e0-5b9c-4bb2-8e0f-a7c2c2a7534b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_6aaf3a9f-16b4-4592-a409-134403d56a42" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_10661794-a54b-4056-85a2-7d7101605ad3" xlink:to="loc_srt_ProductOrServiceAxis_6aaf3a9f-16b4-4592-a409-134403d56a42" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_6aaf3a9f-16b4-4592-a409-134403d56a42_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_6aaf3a9f-16b4-4592-a409-134403d56a42" xlink:to="loc_srt_ProductsAndServicesDomain_6aaf3a9f-16b4-4592-a409-134403d56a42_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_a8c4559b-012d-4919-97cb-0f88f5938cb5" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_6aaf3a9f-16b4-4592-a409-134403d56a42" xlink:to="loc_srt_ProductsAndServicesDomain_a8c4559b-012d-4919-97cb-0f88f5938cb5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_LongTermContractsOnElectricPowerAndPropulsionProgramsMember_f91b15fc-6889-495c-832d-7d0d1806c60f" xlink:href="drs-20251231.xsd#drs_LongTermContractsOnElectricPowerAndPropulsionProgramsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_a8c4559b-012d-4919-97cb-0f88f5938cb5" xlink:to="loc_drs_LongTermContractsOnElectricPowerAndPropulsionProgramsMember_f91b15fc-6889-495c-832d-7d0d1806c60f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligation_45c7827f-c100-40f2-8ca5-bfe5edfb9cf8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_3d2d16e0-8046-4fec-8219-5db0f80e645b" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligation_45c7827f-c100-40f2-8ca5-bfe5edfb9cf8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationPercentage_141aa54a-7425-4e15-886f-dcab525266d0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligationPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_3d2d16e0-8046-4fec-8219-5db0f80e645b" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationPercentage_141aa54a-7425-4e15-886f-dcab525266d0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_b76e65ed-826d-4a93-af07-db573580f508" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_3d2d16e0-8046-4fec-8219-5db0f80e645b" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_b76e65ed-826d-4a93-af07-db573580f508" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.leonardodrs.com/role/RevenuefromContractswithCustomersRemainingPerformanceObligationsNarrativeDetails_1" xlink:type="simple" xlink:href="drs-20251231.xsd#RevenuefromContractswithCustomersRemainingPerformanceObligationsNarrativeDetails_1"/>
  <link:definitionLink xlink:role="http://www.leonardodrs.com/role/RevenuefromContractswithCustomersRemainingPerformanceObligationsNarrativeDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_3d2d16e0-8046-4fec-8219-5db0f80e645b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_10661794-a54b-4056-85a2-7d7101605ad3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_3d2d16e0-8046-4fec-8219-5db0f80e645b" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_10661794-a54b-4056-85a2-7d7101605ad3" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_6aaf3a9f-16b4-4592-a409-134403d56a42" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_10661794-a54b-4056-85a2-7d7101605ad3" xlink:to="loc_srt_ProductOrServiceAxis_6aaf3a9f-16b4-4592-a409-134403d56a42" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_6aaf3a9f-16b4-4592-a409-134403d56a42_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_6aaf3a9f-16b4-4592-a409-134403d56a42" xlink:to="loc_srt_ProductsAndServicesDomain_6aaf3a9f-16b4-4592-a409-134403d56a42_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_a8c4559b-012d-4919-97cb-0f88f5938cb5" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_6aaf3a9f-16b4-4592-a409-134403d56a42" xlink:to="loc_srt_ProductsAndServicesDomain_a8c4559b-012d-4919-97cb-0f88f5938cb5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_LongTermContractsOnElectricPowerAndPropulsionProgramsMember_f91b15fc-6889-495c-832d-7d0d1806c60f" xlink:href="drs-20251231.xsd#drs_LongTermContractsOnElectricPowerAndPropulsionProgramsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_a8c4559b-012d-4919-97cb-0f88f5938cb5" xlink:to="loc_drs_LongTermContractsOnElectricPowerAndPropulsionProgramsMember_f91b15fc-6889-495c-832d-7d0d1806c60f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligation_45c7827f-c100-40f2-8ca5-bfe5edfb9cf8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_3d2d16e0-8046-4fec-8219-5db0f80e645b" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligation_45c7827f-c100-40f2-8ca5-bfe5edfb9cf8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationPercentage_141aa54a-7425-4e15-886f-dcab525266d0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligationPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_3d2d16e0-8046-4fec-8219-5db0f80e645b" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationPercentage_141aa54a-7425-4e15-886f-dcab525266d0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_b76e65ed-826d-4a93-af07-db573580f508" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_3d2d16e0-8046-4fec-8219-5db0f80e645b" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_b76e65ed-826d-4a93-af07-db573580f508" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.leonardodrs.com/role/RevenuefromContractswithCustomersDisaggregationofRevenueDetails" xlink:type="simple" xlink:href="drs-20251231.xsd#RevenuefromContractswithCustomersDisaggregationofRevenueDetails"/>
  <link:definitionLink xlink:role="http://www.leonardodrs.com/role/RevenuefromContractswithCustomersDisaggregationofRevenueDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_16c9449a-dd0a-419c-a107-c160e0ed5ce2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_0bcc4447-7d17-42c9-9ba2-693febbe8a78" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_16c9449a-dd0a-419c-a107-c160e0ed5ce2" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_0bcc4447-7d17-42c9-9ba2-693febbe8a78" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_e352b699-3fa8-4dd0-928c-691f449083c5" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_0bcc4447-7d17-42c9-9ba2-693febbe8a78" xlink:to="loc_srt_StatementGeographicalAxis_e352b699-3fa8-4dd0-928c-691f449083c5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_e352b699-3fa8-4dd0-928c-691f449083c5_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_e352b699-3fa8-4dd0-928c-691f449083c5" xlink:to="loc_srt_SegmentGeographicalDomain_e352b699-3fa8-4dd0-928c-691f449083c5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_866f5ceb-49f3-4da4-84f1-c6df313be5ee" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_e352b699-3fa8-4dd0-928c-691f449083c5" xlink:to="loc_srt_SegmentGeographicalDomain_866f5ceb-49f3-4da4-84f1-c6df313be5ee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_c19e8ba0-948e-4929-89d2-246cbae74dd8" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_866f5ceb-49f3-4da4-84f1-c6df313be5ee" xlink:to="loc_country_US_c19e8ba0-948e-4929-89d2-246cbae74dd8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonUsMember_e0728d43-6772-42a6-8a1b-775fc8489452" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NonUsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_866f5ceb-49f3-4da4-84f1-c6df313be5ee" xlink:to="loc_us-gaap_NonUsMember_e0728d43-6772-42a6-8a1b-775fc8489452" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_fcbe448e-95de-4a4e-8736-8d213ed4e052" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_0bcc4447-7d17-42c9-9ba2-693febbe8a78" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_fcbe448e-95de-4a4e-8736-8d213ed4e052" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_fcbe448e-95de-4a4e-8736-8d213ed4e052_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_fcbe448e-95de-4a4e-8736-8d213ed4e052" xlink:to="loc_us-gaap_SegmentDomain_fcbe448e-95de-4a4e-8736-8d213ed4e052_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_7bb5e8ad-03fb-4723-abe2-8f7fd3da4c51" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_fcbe448e-95de-4a4e-8736-8d213ed4e052" xlink:to="loc_us-gaap_SegmentDomain_7bb5e8ad-03fb-4723-abe2-8f7fd3da4c51" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_AdvancedSensingAndComputingSegmentMember_1d0fe387-b0b4-43f3-bd33-6c04ae67f3d0" xlink:href="drs-20251231.xsd#drs_AdvancedSensingAndComputingSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_7bb5e8ad-03fb-4723-abe2-8f7fd3da4c51" xlink:to="loc_drs_AdvancedSensingAndComputingSegmentMember_1d0fe387-b0b4-43f3-bd33-6c04ae67f3d0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_IntegratedMissionSystemsSegmentMember_5ebabb19-05d5-439f-8607-2f531d90ee96" xlink:href="drs-20251231.xsd#drs_IntegratedMissionSystemsSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_7bb5e8ad-03fb-4723-abe2-8f7fd3da4c51" xlink:to="loc_drs_IntegratedMissionSystemsSegmentMember_5ebabb19-05d5-439f-8607-2f531d90ee96" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_4b7ad08b-e533-47e8-9668-5382e4a9f631" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_0bcc4447-7d17-42c9-9ba2-693febbe8a78" xlink:to="loc_srt_ConsolidationItemsAxis_4b7ad08b-e533-47e8-9668-5382e4a9f631" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_4b7ad08b-e533-47e8-9668-5382e4a9f631_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_4b7ad08b-e533-47e8-9668-5382e4a9f631" xlink:to="loc_srt_ConsolidationItemsDomain_4b7ad08b-e533-47e8-9668-5382e4a9f631_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_a8175d55-9c11-4d21-9a5c-185a8f67fe82" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_4b7ad08b-e533-47e8-9668-5382e4a9f631" xlink:to="loc_srt_ConsolidationItemsDomain_a8175d55-9c11-4d21-9a5c-185a8f67fe82" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntersegmentEliminationMember_a514a613-104d-4686-815b-aecb52041928" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IntersegmentEliminationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_a8175d55-9c11-4d21-9a5c-185a8f67fe82" xlink:to="loc_us-gaap_IntersegmentEliminationMember_a514a613-104d-4686-815b-aecb52041928" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_8aaee9e0-a9f6-4880-9f65-8261d0af5466" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_a8175d55-9c11-4d21-9a5c-185a8f67fe82" xlink:to="loc_us-gaap_OperatingSegmentsMember_8aaee9e0-a9f6-4880-9f65-8261d0af5466" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerBasisOfPricingAxis_cf5906e0-4cbc-44b5-8266-fba236d8f3cc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ContractWithCustomerBasisOfPricingAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_0bcc4447-7d17-42c9-9ba2-693febbe8a78" xlink:to="loc_us-gaap_ContractWithCustomerBasisOfPricingAxis_cf5906e0-4cbc-44b5-8266-fba236d8f3cc" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_cf5906e0-4cbc-44b5-8266-fba236d8f3cc_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ContractWithCustomerBasisOfPricingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ContractWithCustomerBasisOfPricingAxis_cf5906e0-4cbc-44b5-8266-fba236d8f3cc" xlink:to="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_cf5906e0-4cbc-44b5-8266-fba236d8f3cc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_eb47369c-015a-4471-b6a7-0709b3db9006" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ContractWithCustomerBasisOfPricingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ContractWithCustomerBasisOfPricingAxis_cf5906e0-4cbc-44b5-8266-fba236d8f3cc" xlink:to="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_eb47369c-015a-4471-b6a7-0709b3db9006" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FixedPriceContractMember_2405d43c-10fd-4c0e-a6f5-5b691d270928" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FixedPriceContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_eb47369c-015a-4471-b6a7-0709b3db9006" xlink:to="loc_us-gaap_FixedPriceContractMember_2405d43c-10fd-4c0e-a6f5-5b691d270928" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TimeAndMaterialsContractMember_f2dcc9c4-1256-4f39-bd68-55b4097e5626" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TimeAndMaterialsContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_eb47369c-015a-4471-b6a7-0709b3db9006" xlink:to="loc_us-gaap_TimeAndMaterialsContractMember_f2dcc9c4-1256-4f39-bd68-55b4097e5626" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerSalesChannelAxis_56aed8f9-5c1f-4c79-b619-bafab62b405f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ContractWithCustomerSalesChannelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_0bcc4447-7d17-42c9-9ba2-693febbe8a78" xlink:to="loc_us-gaap_ContractWithCustomerSalesChannelAxis_56aed8f9-5c1f-4c79-b619-bafab62b405f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerSalesChannelDomain_56aed8f9-5c1f-4c79-b619-bafab62b405f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ContractWithCustomerSalesChannelDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelAxis_56aed8f9-5c1f-4c79-b619-bafab62b405f" xlink:to="loc_us-gaap_ContractWithCustomerSalesChannelDomain_56aed8f9-5c1f-4c79-b619-bafab62b405f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerSalesChannelDomain_a88ae4b9-be26-408b-8bfc-fde60a70e45b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ContractWithCustomerSalesChannelDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelAxis_56aed8f9-5c1f-4c79-b619-bafab62b405f" xlink:to="loc_us-gaap_ContractWithCustomerSalesChannelDomain_a88ae4b9-be26-408b-8bfc-fde60a70e45b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SalesChannelDirectlyToConsumerMember_7ab473e6-2afb-4e1e-93c4-7a94bb26187a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SalesChannelDirectlyToConsumerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelDomain_a88ae4b9-be26-408b-8bfc-fde60a70e45b" xlink:to="loc_us-gaap_SalesChannelDirectlyToConsumerMember_7ab473e6-2afb-4e1e-93c4-7a94bb26187a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SalesChannelThroughIntermediaryMember_e6b0beec-237b-40ce-9141-16c6ad5e61bb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SalesChannelThroughIntermediaryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelDomain_a88ae4b9-be26-408b-8bfc-fde60a70e45b" xlink:to="loc_us-gaap_SalesChannelThroughIntermediaryMember_e6b0beec-237b-40ce-9141-16c6ad5e61bb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_9109b4e8-799c-4454-acb5-b47bbd7a90a9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_16c9449a-dd0a-419c-a107-c160e0ed5ce2" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_9109b4e8-799c-4454-acb5-b47bbd7a90a9" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.leonardodrs.com/role/PropertyPlantandEquipmentScheduleofPropertyPlantandEquipmentDetails" xlink:type="simple" xlink:href="drs-20251231.xsd#PropertyPlantandEquipmentScheduleofPropertyPlantandEquipmentDetails"/>
  <link:definitionLink xlink:role="http://www.leonardodrs.com/role/PropertyPlantandEquipmentScheduleofPropertyPlantandEquipmentDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_72be5bb2-63f4-495a-9de3-071a3d11a511" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_05c8f474-28b8-4e90-8350-f7caca2211bb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_72be5bb2-63f4-495a-9de3-071a3d11a511" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_05c8f474-28b8-4e90-8350-f7caca2211bb" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_e70f0917-97bd-49be-aa18-e701385df81e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_05c8f474-28b8-4e90-8350-f7caca2211bb" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_e70f0917-97bd-49be-aa18-e701385df81e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_e70f0917-97bd-49be-aa18-e701385df81e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_e70f0917-97bd-49be-aa18-e701385df81e" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_e70f0917-97bd-49be-aa18-e701385df81e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_8f273b08-e606-4f23-a0ce-53edbf691d9f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_e70f0917-97bd-49be-aa18-e701385df81e" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_8f273b08-e606-4f23-a0ce-53edbf691d9f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LandBuildingsAndImprovementsMember_078bdc99-6567-44e4-b660-2dedcf03b114" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LandBuildingsAndImprovementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_8f273b08-e606-4f23-a0ce-53edbf691d9f" xlink:to="loc_us-gaap_LandBuildingsAndImprovementsMember_078bdc99-6567-44e4-b660-2dedcf03b114" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MachineryAndEquipmentMember_8323bb49-d493-43da-a002-b26b094c8526" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MachineryAndEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_8f273b08-e606-4f23-a0ce-53edbf691d9f" xlink:to="loc_us-gaap_MachineryAndEquipmentMember_8323bb49-d493-43da-a002-b26b094c8526" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_EquipmentAndOtherCapitalizedPropertyPlantAndEquipmentMember_2cab783b-8afc-430b-8409-34e1324577f8" xlink:href="drs-20251231.xsd#drs_EquipmentAndOtherCapitalizedPropertyPlantAndEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_8f273b08-e606-4f23-a0ce-53edbf691d9f" xlink:to="loc_drs_EquipmentAndOtherCapitalizedPropertyPlantAndEquipmentMember_2cab783b-8afc-430b-8409-34e1324577f8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization_d766ef42-d50a-417b-a316-3193a5594c05" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_72be5bb2-63f4-495a-9de3-071a3d11a511" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization_d766ef42-d50a-417b-a316-3193a5594c05" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization_ec63e9b8-3556-45df-8213-86a8588c05f0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_72be5bb2-63f4-495a-9de3-071a3d11a511" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization_ec63e9b8-3556-45df-8213-86a8588c05f0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization_ab0403a5-cfc3-4c60-a3bf-e5345a351938" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_72be5bb2-63f4-495a-9de3-071a3d11a511" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization_ab0403a5-cfc3-4c60-a3bf-e5345a351938" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.leonardodrs.com/role/GoodwillScheduleofGoodwillDetails" xlink:type="simple" xlink:href="drs-20251231.xsd#GoodwillScheduleofGoodwillDetails"/>
  <link:definitionLink xlink:role="http://www.leonardodrs.com/role/GoodwillScheduleofGoodwillDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillLineItems_aa9a1ecb-219e-4c5b-8a10-b7b755c261ba" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GoodwillLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfGoodwillTable_f7d87fbf-6c28-44e6-ba0d-b45a42d31e2f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfGoodwillTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_GoodwillLineItems_aa9a1ecb-219e-4c5b-8a10-b7b755c261ba" xlink:to="loc_us-gaap_ScheduleOfGoodwillTable_f7d87fbf-6c28-44e6-ba0d-b45a42d31e2f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_4778f5be-ab24-4dc7-9cac-d595f1259dad" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_f7d87fbf-6c28-44e6-ba0d-b45a42d31e2f" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_4778f5be-ab24-4dc7-9cac-d595f1259dad" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_4778f5be-ab24-4dc7-9cac-d595f1259dad_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_4778f5be-ab24-4dc7-9cac-d595f1259dad" xlink:to="loc_us-gaap_SegmentDomain_4778f5be-ab24-4dc7-9cac-d595f1259dad_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_4f672557-149e-4d7a-9d30-a2fd0dde0d78" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_4778f5be-ab24-4dc7-9cac-d595f1259dad" xlink:to="loc_us-gaap_SegmentDomain_4f672557-149e-4d7a-9d30-a2fd0dde0d78" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_AdvancedSensingAndComputingSegmentMember_dc19156c-9e04-42cc-a337-354bad7363d6" xlink:href="drs-20251231.xsd#drs_AdvancedSensingAndComputingSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_4f672557-149e-4d7a-9d30-a2fd0dde0d78" xlink:to="loc_drs_AdvancedSensingAndComputingSegmentMember_dc19156c-9e04-42cc-a337-354bad7363d6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_IntegratedMissionSystemsSegmentMember_54ed7fcc-2239-41ee-9b9a-597a8d4d0cc7" xlink:href="drs-20251231.xsd#drs_IntegratedMissionSystemsSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_4f672557-149e-4d7a-9d30-a2fd0dde0d78" xlink:to="loc_drs_IntegratedMissionSystemsSegmentMember_54ed7fcc-2239-41ee-9b9a-597a8d4d0cc7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_019b9f53-cc55-7589-83ca-9fab2ef8af65" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_aa9a1ecb-219e-4c5b-8a10-b7b755c261ba" xlink:to="loc_us-gaap_Goodwill_019b9f53-cc55-7589-83ca-9fab2ef8af65" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.leonardodrs.com/role/GoodwillNarrativeDetails" xlink:type="simple" xlink:href="drs-20251231.xsd#GoodwillNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.leonardodrs.com/role/GoodwillNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillLineItems_03022281-ae0c-4497-afe8-313dff9d3c8e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GoodwillLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfGoodwillTable_77141bbf-7057-42d6-a37a-46d5bca4fa9c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfGoodwillTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_GoodwillLineItems_03022281-ae0c-4497-afe8-313dff9d3c8e" xlink:to="loc_us-gaap_ScheduleOfGoodwillTable_77141bbf-7057-42d6-a37a-46d5bca4fa9c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_82cb2b10-bdb9-4d0d-9892-62987e237812" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_77141bbf-7057-42d6-a37a-46d5bca4fa9c" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_82cb2b10-bdb9-4d0d-9892-62987e237812" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_82cb2b10-bdb9-4d0d-9892-62987e237812_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_82cb2b10-bdb9-4d0d-9892-62987e237812" xlink:to="loc_us-gaap_SegmentDomain_82cb2b10-bdb9-4d0d-9892-62987e237812_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_dfba2f55-cfa8-4d45-a3b3-a99a51330de9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_82cb2b10-bdb9-4d0d-9892-62987e237812" xlink:to="loc_us-gaap_SegmentDomain_dfba2f55-cfa8-4d45-a3b3-a99a51330de9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_AdvancedSensingAndComputingSegmentMember_42b7c155-20a6-44b2-ac2d-31bbb77f3922" xlink:href="drs-20251231.xsd#drs_AdvancedSensingAndComputingSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_dfba2f55-cfa8-4d45-a3b3-a99a51330de9" xlink:to="loc_drs_AdvancedSensingAndComputingSegmentMember_42b7c155-20a6-44b2-ac2d-31bbb77f3922" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_IntegratedMissionSystemsSegmentMember_e23edeba-2494-4b38-a7e5-0ef80f129640" xlink:href="drs-20251231.xsd#drs_IntegratedMissionSystemsSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_dfba2f55-cfa8-4d45-a3b3-a99a51330de9" xlink:to="loc_drs_IntegratedMissionSystemsSegmentMember_e23edeba-2494-4b38-a7e5-0ef80f129640" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillImpairedAccumulatedImpairmentLoss_50c3ebcf-44b7-4745-b3da-c1bfe7e0c04e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GoodwillImpairedAccumulatedImpairmentLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_03022281-ae0c-4497-afe8-313dff9d3c8e" xlink:to="loc_us-gaap_GoodwillImpairedAccumulatedImpairmentLoss_50c3ebcf-44b7-4745-b3da-c1bfe7e0c04e" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.leonardodrs.com/role/IntangibleAssetsScheduleofFiniteLivedIntangibleAssetsDetails" xlink:type="simple" xlink:href="drs-20251231.xsd#IntangibleAssetsScheduleofFiniteLivedIntangibleAssetsDetails"/>
  <link:definitionLink xlink:role="http://www.leonardodrs.com/role/IntangibleAssetsScheduleofFiniteLivedIntangibleAssetsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_0aca63d9-cec3-473b-a0a1-175638e62dd5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_a114022a-d76a-49d8-9338-94ac95f4dad7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_0aca63d9-cec3-473b-a0a1-175638e62dd5" xlink:to="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_a114022a-d76a-49d8-9338-94ac95f4dad7" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_c8e65f5a-9511-444b-9a17-998bc73e70cb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_a114022a-d76a-49d8-9338-94ac95f4dad7" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_c8e65f5a-9511-444b-9a17-998bc73e70cb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_c8e65f5a-9511-444b-9a17-998bc73e70cb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_c8e65f5a-9511-444b-9a17-998bc73e70cb" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_c8e65f5a-9511-444b-9a17-998bc73e70cb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_c1e676d4-0ac3-4d96-8643-58b2e3c01110" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_c8e65f5a-9511-444b-9a17-998bc73e70cb" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_c1e676d4-0ac3-4d96-8643-58b2e3c01110" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_AcquiredIntangibleAssetsMember_5d912ea2-0c93-4a90-92bd-c96702b663e9" xlink:href="drs-20251231.xsd#drs_AcquiredIntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_c1e676d4-0ac3-4d96-8643-58b2e3c01110" xlink:to="loc_drs_AcquiredIntangibleAssetsMember_5d912ea2-0c93-4a90-92bd-c96702b663e9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_PatentsAndLicenseMember_a0b67653-5510-4f91-9d96-0cd55d74db54" xlink:href="drs-20251231.xsd#drs_PatentsAndLicenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_c1e676d4-0ac3-4d96-8643-58b2e3c01110" xlink:to="loc_drs_PatentsAndLicenseMember_a0b67653-5510-4f91-9d96-0cd55d74db54" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_683b9084-38b8-4e7c-bfa7-4aad48c826f8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_0aca63d9-cec3-473b-a0a1-175638e62dd5" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_683b9084-38b8-4e7c-bfa7-4aad48c826f8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_dd66b675-1ba2-4e05-b7ce-f48cee2a0a14" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_0aca63d9-cec3-473b-a0a1-175638e62dd5" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_dd66b675-1ba2-4e05-b7ce-f48cee2a0a14" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_c4dd08ca-e5aa-4bab-b4f6-6d54889e67ce" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_0aca63d9-cec3-473b-a0a1-175638e62dd5" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsNet_c4dd08ca-e5aa-4bab-b4f6-6d54889e67ce" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.leonardodrs.com/role/IntangibleAssetsNarrativeDetails" xlink:type="simple" xlink:href="drs-20251231.xsd#IntangibleAssetsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.leonardodrs.com/role/IntangibleAssetsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_6ed0c5f2-d5cb-4f11-9730-06bf3e448096" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_f594daa4-9569-4cde-afda-90dcfb6705b1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_6ed0c5f2-d5cb-4f11-9730-06bf3e448096" xlink:to="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_f594daa4-9569-4cde-afda-90dcfb6705b1" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_15ff3cfb-380a-41a3-b3df-36a337944941" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_f594daa4-9569-4cde-afda-90dcfb6705b1" xlink:to="loc_srt_RangeAxis_15ff3cfb-380a-41a3-b3df-36a337944941" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_15ff3cfb-380a-41a3-b3df-36a337944941_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_15ff3cfb-380a-41a3-b3df-36a337944941" xlink:to="loc_srt_RangeMember_15ff3cfb-380a-41a3-b3df-36a337944941_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_91282214-4fce-4245-9a38-af7f1f6c569a" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_15ff3cfb-380a-41a3-b3df-36a337944941" xlink:to="loc_srt_RangeMember_91282214-4fce-4245-9a38-af7f1f6c569a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_159f831b-5416-4619-a40a-574d0c52d94d" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_91282214-4fce-4245-9a38-af7f1f6c569a" xlink:to="loc_srt_MinimumMember_159f831b-5416-4619-a40a-574d0c52d94d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_ef5c3d4f-e89b-4a94-a2bc-bf177b8232fc" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_91282214-4fce-4245-9a38-af7f1f6c569a" xlink:to="loc_srt_MaximumMember_ef5c3d4f-e89b-4a94-a2bc-bf177b8232fc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_2bafbf0a-d1b3-420e-8484-acdca12b0de0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_f594daa4-9569-4cde-afda-90dcfb6705b1" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_2bafbf0a-d1b3-420e-8484-acdca12b0de0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_2bafbf0a-d1b3-420e-8484-acdca12b0de0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_2bafbf0a-d1b3-420e-8484-acdca12b0de0" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_2bafbf0a-d1b3-420e-8484-acdca12b0de0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_2ac1fd29-61e6-46df-9097-43c3eb9b452e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_2bafbf0a-d1b3-420e-8484-acdca12b0de0" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_2ac1fd29-61e6-46df-9097-43c3eb9b452e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_AcquiredIntangibleAssetsMember_9f6f5f1d-ee9a-497c-aea9-1541fafdda24" xlink:href="drs-20251231.xsd#drs_AcquiredIntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_2ac1fd29-61e6-46df-9097-43c3eb9b452e" xlink:to="loc_drs_AcquiredIntangibleAssetsMember_9f6f5f1d-ee9a-497c-aea9-1541fafdda24" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TechnologyBasedIntangibleAssetsMember_4da9fbf7-319a-4fdc-baaa-7de6f85cc845" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TechnologyBasedIntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_2ac1fd29-61e6-46df-9097-43c3eb9b452e" xlink:to="loc_us-gaap_TechnologyBasedIntangibleAssetsMember_4da9fbf7-319a-4fdc-baaa-7de6f85cc845" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_ef537abd-0203-4b12-b543-6ba7a6d44bce" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_2ac1fd29-61e6-46df-9097-43c3eb9b452e" xlink:to="loc_us-gaap_CustomerRelationshipsMember_ef537abd-0203-4b12-b543-6ba7a6d44bce" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_PatentsAndLicenseMember_7568a0e0-3ebf-4f80-9b64-afd4a0d6855b" xlink:href="drs-20251231.xsd#drs_PatentsAndLicenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_2ac1fd29-61e6-46df-9097-43c3eb9b452e" xlink:to="loc_drs_PatentsAndLicenseMember_7568a0e0-3ebf-4f80-9b64-afd4a0d6855b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_19cda299-207f-4661-be08-3926393d3d7e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_f594daa4-9569-4cde-afda-90dcfb6705b1" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_19cda299-207f-4661-be08-3926393d3d7e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_19cda299-207f-4661-be08-3926393d3d7e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_19cda299-207f-4661-be08-3926393d3d7e" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_19cda299-207f-4661-be08-3926393d3d7e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_21182de0-ba2d-4480-9d5d-6242be833dba" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_19cda299-207f-4661-be08-3926393d3d7e" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_21182de0-ba2d-4480-9d5d-6242be833dba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_RADAElectronicIndustriesLtdMember_7a65c218-9741-4b14-80c3-ef21421c3bf5" xlink:href="drs-20251231.xsd#drs_RADAElectronicIndustriesLtdMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_21182de0-ba2d-4480-9d5d-6242be833dba" xlink:to="loc_drs_RADAElectronicIndustriesLtdMember_7a65c218-9741-4b14-80c3-ef21421c3bf5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_e914f595-c5af-4431-aafd-bbebca6c9a09" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AmortizationOfIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_6ed0c5f2-d5cb-4f11-9730-06bf3e448096" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_e914f595-c5af-4431-aafd-bbebca6c9a09" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_cc984e41-0635-493d-a8a9-221bde79099f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_6ed0c5f2-d5cb-4f11-9730-06bf3e448096" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_cc984e41-0635-493d-a8a9-221bde79099f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill_0f61129f-8180-4f53-b373-6d2b71318b82" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_6ed0c5f2-d5cb-4f11-9730-06bf3e448096" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill_0f61129f-8180-4f53-b373-6d2b71318b82" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.leonardodrs.com/role/LeasesNarrativeDetails" xlink:type="simple" xlink:href="drs-20251231.xsd#LeasesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.leonardodrs.com/role/LeasesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecordedUnconditionalPurchaseObligationLineItems_019c4bca-8531-7580-aef7-6e0ca5714205" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UnrecordedUnconditionalPurchaseObligationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecordedUnconditionalPurchaseObligationTable_019c4bca-8531-7782-a28e-3a079d4b31fb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UnrecordedUnconditionalPurchaseObligationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_UnrecordedUnconditionalPurchaseObligationLineItems_019c4bca-8531-7580-aef7-6e0ca5714205" xlink:to="loc_us-gaap_UnrecordedUnconditionalPurchaseObligationTable_019c4bca-8531-7782-a28e-3a079d4b31fb" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis_019c4bca-8531-7949-b002-59a876fb71ca" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_UnrecordedUnconditionalPurchaseObligationTable_019c4bca-8531-7782-a28e-3a079d4b31fb" xlink:to="loc_us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis_019c4bca-8531-7949-b002-59a876fb71ca" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnconditionalPurchaseObligationCategoryOfGoodsOrServicesAcquiredDomain_019c4bca-8531-7949-b002-59a876fb71ca_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UnconditionalPurchaseObligationCategoryOfGoodsOrServicesAcquiredDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis_019c4bca-8531-7949-b002-59a876fb71ca" xlink:to="loc_us-gaap_UnconditionalPurchaseObligationCategoryOfGoodsOrServicesAcquiredDomain_019c4bca-8531-7949-b002-59a876fb71ca_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnconditionalPurchaseObligationCategoryOfGoodsOrServicesAcquiredDomain_019c4bca-8531-7e95-b80a-f991ce6af96f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UnconditionalPurchaseObligationCategoryOfGoodsOrServicesAcquiredDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis_019c4bca-8531-7949-b002-59a876fb71ca" xlink:to="loc_us-gaap_UnconditionalPurchaseObligationCategoryOfGoodsOrServicesAcquiredDomain_019c4bca-8531-7e95-b80a-f991ce6af96f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLeaseNotYetCommencedMember_019c4bca-8531-7a9e-a441-0a759a104d03" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLeaseLeaseNotYetCommencedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_UnconditionalPurchaseObligationCategoryOfGoodsOrServicesAcquiredDomain_019c4bca-8531-7e95-b80a-f991ce6af96f" xlink:to="loc_us-gaap_OperatingLeaseLeaseNotYetCommencedMember_019c4bca-8531-7a9e-a441-0a759a104d03" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceSheetAmount_019c4bca-8531-77c6-a24f-90a13cfa9d92" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceSheetAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_UnrecordedUnconditionalPurchaseObligationLineItems_019c4bca-8531-7580-aef7-6e0ca5714205" xlink:to="loc_us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceSheetAmount_019c4bca-8531-77c6-a24f-90a13cfa9d92" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseLeaseNotYetCommencedTermOfContract1_019c4bca-8531-74c5-844a-39a3afdf0c7c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LesseeOperatingLeaseLeaseNotYetCommencedTermOfContract1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_UnrecordedUnconditionalPurchaseObligationLineItems_019c4bca-8531-7580-aef7-6e0ca5714205" xlink:to="loc_us-gaap_LesseeOperatingLeaseLeaseNotYetCommencedTermOfContract1_019c4bca-8531-74c5-844a-39a3afdf0c7c" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.leonardodrs.com/role/IncomeTaxesNarrativeDetails" xlink:type="simple" xlink:href="drs-20251231.xsd#IncomeTaxesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.leonardodrs.com/role/IncomeTaxesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLossCarryforwardsLineItems_d9664135-e495-4c0f-9e25-3e7b25f3b596" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLossCarryforwardsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLossCarryforwardsTable_a9a4478d-4bab-4ec8-825e-d812d204bb07" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLossCarryforwardsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_d9664135-e495-4c0f-9e25-3e7b25f3b596" xlink:to="loc_us-gaap_OperatingLossCarryforwardsTable_a9a4478d-4bab-4ec8-825e-d812d204bb07" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityNameAxis_28738afc-2875-44e8-b381-492c9db24df1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OperatingLossCarryforwardsTable_a9a4478d-4bab-4ec8-825e-d812d204bb07" xlink:to="loc_us-gaap_IncomeTaxAuthorityNameAxis_28738afc-2875-44e8-b381-492c9db24df1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityNameDomain_28738afc-2875-44e8-b381-492c9db24df1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeTaxAuthorityNameAxis_28738afc-2875-44e8-b381-492c9db24df1" xlink:to="loc_us-gaap_IncomeTaxAuthorityNameDomain_28738afc-2875-44e8-b381-492c9db24df1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityNameDomain_a0ec9d34-faa0-41f9-9f31-52c442277ad2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeTaxAuthorityNameAxis_28738afc-2875-44e8-b381-492c9db24df1" xlink:to="loc_us-gaap_IncomeTaxAuthorityNameDomain_a0ec9d34-faa0-41f9-9f31-52c442277ad2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InternalRevenueServiceIRSMember_724c6748-6032-4f85-bd7c-1a94b09d7db3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InternalRevenueServiceIRSMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityNameDomain_a0ec9d34-faa0-41f9-9f31-52c442277ad2" xlink:to="loc_us-gaap_InternalRevenueServiceIRSMember_724c6748-6032-4f85-bd7c-1a94b09d7db3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityAxis_22ea7a62-fe72-49e1-8b04-ecc42e7fcfb5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OperatingLossCarryforwardsTable_a9a4478d-4bab-4ec8-825e-d812d204bb07" xlink:to="loc_us-gaap_IncomeTaxAuthorityAxis_22ea7a62-fe72-49e1-8b04-ecc42e7fcfb5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_22ea7a62-fe72-49e1-8b04-ecc42e7fcfb5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_22ea7a62-fe72-49e1-8b04-ecc42e7fcfb5" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_22ea7a62-fe72-49e1-8b04-ecc42e7fcfb5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_d9c57f4f-0809-42c0-ae5e-28529069b8a9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_22ea7a62-fe72-49e1-8b04-ecc42e7fcfb5" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_d9c57f4f-0809-42c0-ae5e-28529069b8a9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DomesticCountryMember_96c7b4e8-5413-4708-b7d0-4f8666b4ea39" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DomesticCountryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_d9c57f4f-0809-42c0-ae5e-28529069b8a9" xlink:to="loc_us-gaap_DomesticCountryMember_96c7b4e8-5413-4708-b7d0-4f8666b4ea39" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCountryMember_b9fd2271-22f8-4578-b1da-e3f30e75ad78" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ForeignCountryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_d9c57f4f-0809-42c0-ae5e-28529069b8a9" xlink:to="loc_us-gaap_ForeignCountryMember_b9fd2271-22f8-4578-b1da-e3f30e75ad78" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StateAndLocalJurisdictionMember_2daca5bd-dd0b-4e5f-843c-15d75447fd63" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StateAndLocalJurisdictionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_d9c57f4f-0809-42c0-ae5e-28529069b8a9" xlink:to="loc_us-gaap_StateAndLocalJurisdictionMember_2daca5bd-dd0b-4e5f-843c-15d75447fd63" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_ab1e9be2-ac92-4932-9fef-2be658346e52" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BalanceSheetLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OperatingLossCarryforwardsTable_a9a4478d-4bab-4ec8-825e-d812d204bb07" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_ab1e9be2-ac92-4932-9fef-2be658346e52" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_ab1e9be2-ac92-4932-9fef-2be658346e52_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_ab1e9be2-ac92-4932-9fef-2be658346e52" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_ab1e9be2-ac92-4932-9fef-2be658346e52_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_9ad3eb4c-22d8-4ccd-a712-f6cb970b5bc2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_ab1e9be2-ac92-4932-9fef-2be658346e52" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_9ad3eb4c-22d8-4ccd-a712-f6cb970b5bc2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_DeferredIncomeTaxAssetsNetMember_8fe6cf0d-5e3d-4e8b-a73b-e3244f503ba5" xlink:href="drs-20251231.xsd#drs_DeferredIncomeTaxAssetsNetMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_9ad3eb4c-22d8-4ccd-a712-f6cb970b5bc2" xlink:to="loc_drs_DeferredIncomeTaxAssetsNetMember_8fe6cf0d-5e3d-4e8b-a73b-e3244f503ba5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLossCarryforwards_cad9485b-b09a-4034-91fe-8a0128d533c3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLossCarryforwards"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_d9664135-e495-4c0f-9e25-3e7b25f3b596" xlink:to="loc_us-gaap_OperatingLossCarryforwards_cad9485b-b09a-4034-91fe-8a0128d533c3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_OperatingLossCarryforwardsLimitationsOnUseAmount_7d0cbb99-37fb-4d28-ae7a-52d8ff6f1d47" xlink:href="drs-20251231.xsd#drs_OperatingLossCarryforwardsLimitationsOnUseAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_d9664135-e495-4c0f-9e25-3e7b25f3b596" xlink:to="loc_drs_OperatingLossCarryforwardsLimitationsOnUseAmount_7d0cbb99-37fb-4d28-ae7a-52d8ff6f1d47" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsValuationAllowance_e9c552ec-57ac-4a05-8d2f-87891f716afa" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredTaxAssetsValuationAllowance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_d9664135-e495-4c0f-9e25-3e7b25f3b596" xlink:to="loc_us-gaap_DeferredTaxAssetsValuationAllowance_e9c552ec-57ac-4a05-8d2f-87891f716afa" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_InflationReductionActOf2022IncomeTaxCreditsPurchased_df5d89ba-438d-4be7-804f-99f44d59af42" xlink:href="drs-20251231.xsd#drs_InflationReductionActOf2022IncomeTaxCreditsPurchased"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_d9664135-e495-4c0f-9e25-3e7b25f3b596" xlink:to="loc_drs_InflationReductionActOf2022IncomeTaxCreditsPurchased_df5d89ba-438d-4be7-804f-99f44d59af42" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_InflationReductionActOf2022PaymentToAcquireIncomeTaxCredit_3962c994-459b-4429-9d5b-44e0a8e62b95" xlink:href="drs-20251231.xsd#drs_InflationReductionActOf2022PaymentToAcquireIncomeTaxCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_d9664135-e495-4c0f-9e25-3e7b25f3b596" xlink:to="loc_drs_InflationReductionActOf2022PaymentToAcquireIncomeTaxCredit_3962c994-459b-4429-9d5b-44e0a8e62b95" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInIncomeTaxes_019c4bd5-9e8a-797b-ad97-65ab37cdfc3f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInIncomeTaxes"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_d9664135-e495-4c0f-9e25-3e7b25f3b596" xlink:to="loc_us-gaap_IncreaseDecreaseInIncomeTaxes_019c4bd5-9e8a-797b-ad97-65ab37cdfc3f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxesPaidNet_5e55578d-4fde-4317-8cf6-dd30f1ddc0ee" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxesPaidNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_d9664135-e495-4c0f-9e25-3e7b25f3b596" xlink:to="loc_us-gaap_IncomeTaxesPaidNet_5e55578d-4fde-4317-8cf6-dd30f1ddc0ee" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecognizedTaxBenefits_e03b131e-667f-445c-87f4-d7bb7b44fe17" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UnrecognizedTaxBenefits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingLossCarryforwardsLineItems_d9664135-e495-4c0f-9e25-3e7b25f3b596" xlink:to="loc_us-gaap_UnrecognizedTaxBenefits_e03b131e-667f-445c-87f4-d7bb7b44fe17" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.leonardodrs.com/role/IncomeTaxesScheduleofIncomeTaxesPaidRefundedDetails" xlink:type="simple" xlink:href="drs-20251231.xsd#IncomeTaxesScheduleofIncomeTaxesPaidRefundedDetails"/>
  <link:definitionLink xlink:role="http://www.leonardodrs.com/role/IncomeTaxesScheduleofIncomeTaxesPaidRefundedDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationLineItems_4e5df268-90cb-45b3-8f3c-779b3ee68111" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationTable_7ebbab47-8ac4-44be-b61d-0397cb4f8955" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateReconciliationLineItems_4e5df268-90cb-45b3-8f3c-779b3ee68111" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateReconciliationTable_7ebbab47-8ac4-44be-b61d-0397cb4f8955" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityAxis_019b019e-15dd-7dab-b71d-10581a9edeb7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateReconciliationTable_7ebbab47-8ac4-44be-b61d-0397cb4f8955" xlink:to="loc_us-gaap_IncomeTaxAuthorityAxis_019b019e-15dd-7dab-b71d-10581a9edeb7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_019b019e-15dd-7dab-b71d-10581a9edeb7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_019b019e-15dd-7dab-b71d-10581a9edeb7" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_019b019e-15dd-7dab-b71d-10581a9edeb7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_019b019e-15dd-76a3-b1f3-1a0ccc8c50d7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_019b019e-15dd-7dab-b71d-10581a9edeb7" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_019b019e-15dd-76a3-b1f3-1a0ccc8c50d7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DomesticCountryMember_019b01a2-187f-7b7d-9f73-325b48f84a43" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DomesticCountryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_019b019e-15dd-76a3-b1f3-1a0ccc8c50d7" xlink:to="loc_us-gaap_DomesticCountryMember_019b01a2-187f-7b7d-9f73-325b48f84a43" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_stpr_PA_019c2205-5679-7491-93c2-9e82a0d8193b" xlink:href="https://xbrl.sec.gov/stpr/2025/stpr-2025.xsd#stpr_PA"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DomesticCountryMember_019b01a2-187f-7b7d-9f73-325b48f84a43" xlink:to="loc_stpr_PA_019c2205-5679-7491-93c2-9e82a0d8193b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stpr_NJ_019c2205-b606-78c9-add5-d6783ee0c893" xlink:href="https://xbrl.sec.gov/stpr/2025/stpr-2025.xsd#stpr_NJ"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DomesticCountryMember_019b01a2-187f-7b7d-9f73-325b48f84a43" xlink:to="loc_stpr_NJ_019c2205-b606-78c9-add5-d6783ee0c893" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_stpr_CA_019c2205-e9e2-71b4-86b8-9b8cf75d47fa" xlink:href="https://xbrl.sec.gov/stpr/2025/stpr-2025.xsd#stpr_CA"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DomesticCountryMember_019b01a2-187f-7b7d-9f73-325b48f84a43" xlink:to="loc_stpr_CA_019c2205-e9e2-71b4-86b8-9b8cf75d47fa" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StateAndLocalTaxJurisdictionOtherMember_019c7cdd-e821-7531-a900-e0407d9387b4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StateAndLocalTaxJurisdictionOtherMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DomesticCountryMember_019b01a2-187f-7b7d-9f73-325b48f84a43" xlink:to="loc_us-gaap_StateAndLocalTaxJurisdictionOtherMember_019c7cdd-e821-7531-a900-e0407d9387b4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxPaidFederalAfterRefundReceived_019b019b-91de-7597-a276-a5a7c4873184" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxPaidFederalAfterRefundReceived"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateReconciliationLineItems_4e5df268-90cb-45b3-8f3c-779b3ee68111" xlink:to="loc_us-gaap_IncomeTaxPaidFederalAfterRefundReceived_019b019b-91de-7597-a276-a5a7c4873184" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxPaidStateAndLocalAfterRefundReceivedAbstract_019b01a4-d8f1-7edf-a97a-d898c4d62a83" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxPaidStateAndLocalAfterRefundReceivedAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateReconciliationLineItems_4e5df268-90cb-45b3-8f3c-779b3ee68111" xlink:to="loc_us-gaap_IncomeTaxPaidStateAndLocalAfterRefundReceivedAbstract_019b01a4-d8f1-7edf-a97a-d898c4d62a83" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxPaidStateAndLocalAfterRefundReceived_019b019d-6f76-743d-8877-1e855190d5cc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxPaidStateAndLocalAfterRefundReceived"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxPaidStateAndLocalAfterRefundReceivedAbstract_019b01a4-d8f1-7edf-a97a-d898c4d62a83" xlink:to="loc_us-gaap_IncomeTaxPaidStateAndLocalAfterRefundReceived_019b019d-6f76-743d-8877-1e855190d5cc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxesPaidNet_8c97680e-2630-4023-8ddc-1e82a196b624" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxesPaidNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateReconciliationLineItems_4e5df268-90cb-45b3-8f3c-779b3ee68111" xlink:to="loc_us-gaap_IncomeTaxesPaidNet_8c97680e-2630-4023-8ddc-1e82a196b624" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.leonardodrs.com/role/DebtScheduleofLongTermDebtDetails" xlink:type="simple" xlink:href="drs-20251231.xsd#DebtScheduleofLongTermDebtDetails"/>
  <link:definitionLink xlink:role="http://www.leonardodrs.com/role/DebtScheduleofLongTermDebtDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_1b6d93c5-596d-430d-881b-23554c7b6b9a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_d7a823f9-698b-4f3a-816a-2d2894f7c2d3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_1b6d93c5-596d-430d-881b-23554c7b6b9a" xlink:to="loc_us-gaap_DebtInstrumentTable_d7a823f9-698b-4f3a-816a-2d2894f7c2d3" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_857937a0-8921-4e69-aa7d-614b36300cde" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_d7a823f9-698b-4f3a-816a-2d2894f7c2d3" xlink:to="loc_us-gaap_DebtInstrumentAxis_857937a0-8921-4e69-aa7d-614b36300cde" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_857937a0-8921-4e69-aa7d-614b36300cde_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_857937a0-8921-4e69-aa7d-614b36300cde" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_857937a0-8921-4e69-aa7d-614b36300cde_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_b998b579-0cce-4281-af79-a0efb85e3b1f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_857937a0-8921-4e69-aa7d-614b36300cde" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_b998b579-0cce-4281-af79-a0efb85e3b1f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_A2022CreditAgreementTermLoanAMember_ae1f7232-cd03-4b83-ad03-935630241ba3" xlink:href="drs-20251231.xsd#drs_A2022CreditAgreementTermLoanAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_b998b579-0cce-4281-af79-a0efb85e3b1f" xlink:to="loc_drs_A2022CreditAgreementTermLoanAMember_ae1f7232-cd03-4b83-ad03-935630241ba3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_f5454780-e653-40b6-b582-800ba03fb693" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_d7a823f9-698b-4f3a-816a-2d2894f7c2d3" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_f5454780-e653-40b6-b582-800ba03fb693" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_f5454780-e653-40b6-b582-800ba03fb693_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_f5454780-e653-40b6-b582-800ba03fb693" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_f5454780-e653-40b6-b582-800ba03fb693_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_721a3538-3254-4fe8-895b-c0e2cabc0b59" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_f5454780-e653-40b6-b582-800ba03fb693" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_721a3538-3254-4fe8-895b-c0e2cabc0b59" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NotesPayableOtherPayablesMember_b931ae75-d513-4152-ae15-420d8c4848d5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NotesPayableOtherPayablesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_721a3538-3254-4fe8-895b-c0e2cabc0b59" xlink:to="loc_us-gaap_NotesPayableOtherPayablesMember_b931ae75-d513-4152-ae15-420d8c4848d5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_7d266941-4005-428f-b2ee-29e4dd5c2b23" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_1b6d93c5-596d-430d-881b-23554c7b6b9a" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_7d266941-4005-428f-b2ee-29e4dd5c2b23" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_FinanceLeaseLiabilityAndOtherLiability_d48e364c-2c3b-4ecb-b71c-71cf2eae9da6" xlink:href="drs-20251231.xsd#drs_FinanceLeaseLiabilityAndOtherLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_1b6d93c5-596d-430d-881b-23554c7b6b9a" xlink:to="loc_drs_FinanceLeaseLiabilityAndOtherLiability_d48e364c-2c3b-4ecb-b71c-71cf2eae9da6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermBorrowings_af4facfe-87d5-4e36-b643-d506d1642ac6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortTermBorrowings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_1b6d93c5-596d-430d-881b-23554c7b6b9a" xlink:to="loc_us-gaap_ShortTermBorrowings_af4facfe-87d5-4e36-b643-d506d1642ac6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_DebtAndFinanceLeaseObligationsGross_d6f6a4ce-246d-42f3-b5a9-098accdf3472" xlink:href="drs-20251231.xsd#drs_DebtAndFinanceLeaseObligationsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_1b6d93c5-596d-430d-881b-23554c7b6b9a" xlink:to="loc_drs_DebtAndFinanceLeaseObligationsGross_d6f6a4ce-246d-42f3-b5a9-098accdf3472" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_3a926ebf-4708-445a-bed2-94cc8e7a8554" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_1b6d93c5-596d-430d-881b-23554c7b6b9a" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_3a926ebf-4708-445a-bed2-94cc8e7a8554" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtAndCapitalLeaseObligations_e0d9a736-01ac-4d0c-bd9e-bba59fe63522" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtAndCapitalLeaseObligations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_1b6d93c5-596d-430d-881b-23554c7b6b9a" xlink:to="loc_us-gaap_DebtAndCapitalLeaseObligations_e0d9a736-01ac-4d0c-bd9e-bba59fe63522" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtCurrent_ff0f9ef1-faa2-4d37-a09b-002a7eaa2475" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_1b6d93c5-596d-430d-881b-23554c7b6b9a" xlink:to="loc_us-gaap_DebtCurrent_ff0f9ef1-faa2-4d37-a09b-002a7eaa2475" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtAndCapitalLeaseObligations_b35a2490-e271-4d73-ba9c-3b5e416585bc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongTermDebtAndCapitalLeaseObligations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_1b6d93c5-596d-430d-881b-23554c7b6b9a" xlink:to="loc_us-gaap_LongTermDebtAndCapitalLeaseObligations_b35a2490-e271-4d73-ba9c-3b5e416585bc" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.leonardodrs.com/role/DebtNarrativeDetails" xlink:type="simple" xlink:href="drs-20251231.xsd#DebtNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.leonardodrs.com/role/DebtNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_488439a5-f135-44a4-8911-32a9c4f335f0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_feff03b1-603d-4cfb-9286-aea078ddcf30" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_488439a5-f135-44a4-8911-32a9c4f335f0" xlink:to="loc_us-gaap_DebtInstrumentTable_feff03b1-603d-4cfb-9286-aea078ddcf30" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_6b24bc68-490f-4a90-85e0-7497e1cf116b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_feff03b1-603d-4cfb-9286-aea078ddcf30" xlink:to="loc_us-gaap_DebtInstrumentAxis_6b24bc68-490f-4a90-85e0-7497e1cf116b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_6b24bc68-490f-4a90-85e0-7497e1cf116b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_6b24bc68-490f-4a90-85e0-7497e1cf116b" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_6b24bc68-490f-4a90-85e0-7497e1cf116b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_4cb39929-6dfb-4c9a-b8c3-bdc1d6b99df8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_6b24bc68-490f-4a90-85e0-7497e1cf116b" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_4cb39929-6dfb-4c9a-b8c3-bdc1d6b99df8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_A2022CreditAgreementMember_0711a8d8-5609-4757-8893-6fb800aba888" xlink:href="drs-20251231.xsd#drs_A2022CreditAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_4cb39929-6dfb-4c9a-b8c3-bdc1d6b99df8" xlink:to="loc_drs_A2022CreditAgreementMember_0711a8d8-5609-4757-8893-6fb800aba888" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_A2022CreditAgreementTermLoanAMember_6a801e2c-7a92-4fbd-b24f-eadad9a1c26a" xlink:href="drs-20251231.xsd#drs_A2022CreditAgreementTermLoanAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_4cb39929-6dfb-4c9a-b8c3-bdc1d6b99df8" xlink:to="loc_drs_A2022CreditAgreementTermLoanAMember_6a801e2c-7a92-4fbd-b24f-eadad9a1c26a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_444ab8e8-9dbb-4cc6-84e6-5246310d9e97" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_4cb39929-6dfb-4c9a-b8c3-bdc1d6b99df8" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_444ab8e8-9dbb-4cc6-84e6-5246310d9e97" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_A2026RevolvingCreditFacilityMember_019c220a-8dc2-7fbe-9d07-c84f72529180" xlink:href="drs-20251231.xsd#drs_A2026RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_4cb39929-6dfb-4c9a-b8c3-bdc1d6b99df8" xlink:to="loc_drs_A2026RevolvingCreditFacilityMember_019c220a-8dc2-7fbe-9d07-c84f72529180" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_FinancialInstitutionCreditFacilitiesMember_3e5edc26-1b2e-42d3-bee3-0c91b2c37a0a" xlink:href="drs-20251231.xsd#drs_FinancialInstitutionCreditFacilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_4cb39929-6dfb-4c9a-b8c3-bdc1d6b99df8" xlink:to="loc_drs_FinancialInstitutionCreditFacilitiesMember_3e5edc26-1b2e-42d3-bee3-0c91b2c37a0a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_fc75cd1d-8bf9-4e45-a099-ddcfb9d34a07" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_feff03b1-603d-4cfb-9286-aea078ddcf30" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_fc75cd1d-8bf9-4e45-a099-ddcfb9d34a07" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_fc75cd1d-8bf9-4e45-a099-ddcfb9d34a07_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_fc75cd1d-8bf9-4e45-a099-ddcfb9d34a07" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_fc75cd1d-8bf9-4e45-a099-ddcfb9d34a07_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_7e77f29b-08ca-4a61-b24c-71ae7569a469" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_fc75cd1d-8bf9-4e45-a099-ddcfb9d34a07" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_7e77f29b-08ca-4a61-b24c-71ae7569a469" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NotesPayableOtherPayablesMember_4ed11958-7e38-493d-959f-4dc55517fa83" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NotesPayableOtherPayablesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_7e77f29b-08ca-4a61-b24c-71ae7569a469" xlink:to="loc_us-gaap_NotesPayableOtherPayablesMember_4ed11958-7e38-493d-959f-4dc55517fa83" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_892916b9-8644-41cd-a231-3989f6ff4b9d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_7e77f29b-08ca-4a61-b24c-71ae7569a469" xlink:to="loc_us-gaap_LineOfCreditMember_892916b9-8644-41cd-a231-3989f6ff4b9d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_62dd856f-9603-406d-a3a8-8608e004fbe8" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_feff03b1-603d-4cfb-9286-aea078ddcf30" xlink:to="loc_srt_RangeAxis_62dd856f-9603-406d-a3a8-8608e004fbe8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_62dd856f-9603-406d-a3a8-8608e004fbe8_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_62dd856f-9603-406d-a3a8-8608e004fbe8" xlink:to="loc_srt_RangeMember_62dd856f-9603-406d-a3a8-8608e004fbe8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_b13b1f4e-7805-4d05-b790-688ca50beb36" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_62dd856f-9603-406d-a3a8-8608e004fbe8" xlink:to="loc_srt_RangeMember_b13b1f4e-7805-4d05-b790-688ca50beb36" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_5d9bc4c4-61ba-4d25-adb0-31aa4f8400db" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_b13b1f4e-7805-4d05-b790-688ca50beb36" xlink:to="loc_srt_MinimumMember_5d9bc4c4-61ba-4d25-adb0-31aa4f8400db" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_d39f4949-cec5-496e-9814-ef426273f13d" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_b13b1f4e-7805-4d05-b790-688ca50beb36" xlink:to="loc_srt_MaximumMember_d39f4949-cec5-496e-9814-ef426273f13d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_019c220b-4e78-7966-8af1-913b312e6e85" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_feff03b1-603d-4cfb-9286-aea078ddcf30" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_019c220b-4e78-7966-8af1-913b312e6e85" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019c220b-4e78-7966-8af1-913b312e6e85_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_019c220b-4e78-7966-8af1-913b312e6e85" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019c220b-4e78-7966-8af1-913b312e6e85_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019c220b-4e78-755b-b340-87e0d5362586" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_019c220b-4e78-7966-8af1-913b312e6e85" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019c220b-4e78-755b-b340-87e0d5362586" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_019c220b-7c1b-7ace-afd4-c0e642f02a2a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_019c220b-4e78-755b-b340-87e0d5362586" xlink:to="loc_us-gaap_SubsequentEventMember_019c220b-7c1b-7ace-afd4-c0e642f02a2a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_d98472a0-d8dc-4af8-9acb-cb7e68ca2f2b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_488439a5-f135-44a4-8911-32a9c4f335f0" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_d98472a0-d8dc-4af8-9acb-cb7e68ca2f2b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_afcafa1d-49c9-4755-8f68-c9e57d73b77d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_488439a5-f135-44a4-8911-32a9c4f335f0" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_afcafa1d-49c9-4755-8f68-c9e57d73b77d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_01def47f-e791-4e77-a822-c9bf95f5fc07" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_488439a5-f135-44a4-8911-32a9c4f335f0" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_01def47f-e791-4e77-a822-c9bf95f5fc07" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_feb3518c-53c1-4eaf-b880-305bc21cf99c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_488439a5-f135-44a4-8911-32a9c4f335f0" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_feb3518c-53c1-4eaf-b880-305bc21cf99c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtFairValue_f5aacbc8-b6f7-410d-a4f1-c3d64408b52d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongTermDebtFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_488439a5-f135-44a4-8911-32a9c4f335f0" xlink:to="loc_us-gaap_LongTermDebtFairValue_f5aacbc8-b6f7-410d-a4f1-c3d64408b52d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfDebt_019c220f-6fbc-7bc3-94fc-a06127b151f1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RepaymentsOfDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_488439a5-f135-44a4-8911-32a9c4f335f0" xlink:to="loc_us-gaap_RepaymentsOfDebt_019c220f-6fbc-7bc3-94fc-a06127b151f1" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityCommitmentFeePercentage_93a41484-3d18-4a88-bb22-896c5c3cad92" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCreditFacilityCommitmentFeePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_488439a5-f135-44a4-8911-32a9c4f335f0" xlink:to="loc_us-gaap_LineOfCreditFacilityCommitmentFeePercentage_93a41484-3d18-4a88-bb22-896c5c3cad92" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCredit_3f1dcd19-3375-4354-b400-e4962878590d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_488439a5-f135-44a4-8911-32a9c4f335f0" xlink:to="loc_us-gaap_LineOfCredit_3f1dcd19-3375-4354-b400-e4962878590d" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtWeightedAverageInterestRate_58d45aaf-cbec-47a3-8282-1f66273657b9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtWeightedAverageInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_488439a5-f135-44a4-8911-32a9c4f335f0" xlink:to="loc_us-gaap_DebtWeightedAverageInterestRate_58d45aaf-cbec-47a3-8282-1f66273657b9" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LettersOfCreditOutstandingAmount_f2112d1b-46bb-4c37-aa4b-c4c3beebd18d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LettersOfCreditOutstandingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_488439a5-f135-44a4-8911-32a9c4f335f0" xlink:to="loc_us-gaap_LettersOfCreditOutstandingAmount_f2112d1b-46bb-4c37-aa4b-c4c3beebd18d" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_FinanceLeaseLiabilityAndOtherLiability_b1197757-320c-47ee-b861-d5822892de5a" xlink:href="drs-20251231.xsd#drs_FinanceLeaseLiabilityAndOtherLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_488439a5-f135-44a4-8911-32a9c4f335f0" xlink:to="loc_drs_FinanceLeaseLiabilityAndOtherLiability_b1197757-320c-47ee-b861-d5822892de5a" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiability_25107420-9ee9-4f4a-969e-8a969c3dcd85" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinanceLeaseLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_488439a5-f135-44a4-8911-32a9c4f335f0" xlink:to="loc_us-gaap_FinanceLeaseLiability_25107420-9ee9-4f4a-969e-8a969c3dcd85" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_OtherFinancingLiability_9d34928f-1d89-4965-ba0e-5319ceb14b7f" xlink:href="drs-20251231.xsd#drs_OtherFinancingLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_488439a5-f135-44a4-8911-32a9c4f335f0" xlink:to="loc_drs_OtherFinancingLiability_9d34928f-1d89-4965-ba0e-5319ceb14b7f" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinanceLeaseLiabilityCurrent_4130edd0-a0f0-47cc-9fa8-18a3cf65e50e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinanceLeaseLiabilityCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_488439a5-f135-44a4-8911-32a9c4f335f0" xlink:to="loc_us-gaap_FinanceLeaseLiabilityCurrent_4130edd0-a0f0-47cc-9fa8-18a3cf65e50e" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentPeriodicPaymentInterest_2a2170ef-3ef0-4caa-817b-2647b7c8b58b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentPeriodicPaymentInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_488439a5-f135-44a4-8911-32a9c4f335f0" xlink:to="loc_us-gaap_DebtInstrumentPeriodicPaymentInterest_2a2170ef-3ef0-4caa-817b-2647b7c8b58b" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateEffectivePercentage_3b8804bb-6bf2-4dc2-8512-e0eea9edb328" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentInterestRateEffectivePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_488439a5-f135-44a4-8911-32a9c4f335f0" xlink:to="loc_us-gaap_DebtInstrumentInterestRateEffectivePercentage_3b8804bb-6bf2-4dc2-8512-e0eea9edb328" xlink:type="arc" order="15"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.leonardodrs.com/role/PensionandOtherPostretirementBenefitsNarrativeDetails" xlink:type="simple" xlink:href="drs-20251231.xsd#PensionandOtherPostretirementBenefitsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.leonardodrs.com/role/PensionandOtherPostretirementBenefitsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_3de335b7-6af1-4ecb-967d-4f73dcd09544" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_ff4691d7-e057-4a67-95ab-14cb23340fe7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_3de335b7-6af1-4ecb-967d-4f73dcd09544" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_ff4691d7-e057-4a67-95ab-14cb23340fe7" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_d9b9d9af-1efd-4de2-aaf0-ef5fc3dda421" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_ff4691d7-e057-4a67-95ab-14cb23340fe7" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_d9b9d9af-1efd-4de2-aaf0-ef5fc3dda421" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_d9b9d9af-1efd-4de2-aaf0-ef5fc3dda421_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_d9b9d9af-1efd-4de2-aaf0-ef5fc3dda421" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_d9b9d9af-1efd-4de2-aaf0-ef5fc3dda421_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_6ebeeda6-4bf2-44a8-a927-8e6bc339d604" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_d9b9d9af-1efd-4de2-aaf0-ef5fc3dda421" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_6ebeeda6-4bf2-44a8-a927-8e6bc339d604" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_PensionPlanAndSupplementalEmployeeRetirementPlanMember_56bf5239-9c4a-4148-bd68-fa6a8b515a1f" xlink:href="drs-20251231.xsd#drs_PensionPlanAndSupplementalEmployeeRetirementPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_6ebeeda6-4bf2-44a8-a927-8e6bc339d604" xlink:to="loc_drs_PensionPlanAndSupplementalEmployeeRetirementPlanMember_56bf5239-9c4a-4148-bd68-fa6a8b515a1f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionPlansDefinedBenefitMember_f4596693-28c7-461f-810e-5f5479070540" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PensionPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_drs_PensionPlanAndSupplementalEmployeeRetirementPlanMember_56bf5239-9c4a-4148-bd68-fa6a8b515a1f" xlink:to="loc_us-gaap_PensionPlansDefinedBenefitMember_f4596693-28c7-461f-810e-5f5479070540" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_75496e54-dde0-4059-a328-d0ecbf677b83" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_ff4691d7-e057-4a67-95ab-14cb23340fe7" xlink:to="loc_srt_CounterpartyNameAxis_75496e54-dde0-4059-a328-d0ecbf677b83" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_75496e54-dde0-4059-a328-d0ecbf677b83_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_75496e54-dde0-4059-a328-d0ecbf677b83" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_75496e54-dde0-4059-a328-d0ecbf677b83_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_09f71804-521d-44de-96dd-3892e07bd886" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_75496e54-dde0-4059-a328-d0ecbf677b83" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_09f71804-521d-44de-96dd-3892e07bd886" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_TerminatedVestedParticipantsMember_375e2a9c-07d2-4f27-bd41-273c234407ba" xlink:href="drs-20251231.xsd#drs_TerminatedVestedParticipantsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_09f71804-521d-44de-96dd-3892e07bd886" xlink:to="loc_drs_TerminatedVestedParticipantsMember_375e2a9c-07d2-4f27-bd41-273c234407ba" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAssetsTransferredToFromPlan_9f36e76d-9851-4f17-bb6d-f9be06c6fd7b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanAssetsTransferredToFromPlan"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_3de335b7-6af1-4ecb-967d-4f73dcd09544" xlink:to="loc_us-gaap_DefinedBenefitPlanAssetsTransferredToFromPlan_9f36e76d-9851-4f17-bb6d-f9be06c6fd7b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_DefinedBenefitPlanPensionPlanTransferNumberOfRetireesAndBeneficiaries_e4d7f81d-0094-4b21-aafd-ac933046d501" xlink:href="drs-20251231.xsd#drs_DefinedBenefitPlanPensionPlanTransferNumberOfRetireesAndBeneficiaries"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_3de335b7-6af1-4ecb-967d-4f73dcd09544" xlink:to="loc_drs_DefinedBenefitPlanPensionPlanTransferNumberOfRetireesAndBeneficiaries_e4d7f81d-0094-4b21-aafd-ac933046d501" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanPlanAssetsBenefitsPaid_98ea0a35-9358-46f5-b292-1e6154dc7171" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanPlanAssetsBenefitsPaid"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_3de335b7-6af1-4ecb-967d-4f73dcd09544" xlink:to="loc_us-gaap_DefinedBenefitPlanPlanAssetsBenefitsPaid_98ea0a35-9358-46f5-b292-1e6154dc7171" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateAccumulatedBenefitObligation_6ec16fb4-34db-49fb-8b95-e844c1a485f6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateAccumulatedBenefitObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_3de335b7-6af1-4ecb-967d-4f73dcd09544" xlink:to="loc_us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateAccumulatedBenefitObligation_6ec16fb4-34db-49fb-8b95-e844c1a485f6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedFutureEmployerContributionsNextFiscalYear_cee53cc7-b852-47b3-9cbb-b7145c12edd6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanExpectedFutureEmployerContributionsNextFiscalYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_3de335b7-6af1-4ecb-967d-4f73dcd09544" xlink:to="loc_us-gaap_DefinedBenefitPlanExpectedFutureEmployerContributionsNextFiscalYear_cee53cc7-b852-47b3-9cbb-b7145c12edd6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedContributionPlanCostRecognized_05b9c0cb-2282-4cdc-8a54-bc2b7d3dcefd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedContributionPlanCostRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_3de335b7-6af1-4ecb-967d-4f73dcd09544" xlink:to="loc_us-gaap_DefinedContributionPlanCostRecognized_05b9c0cb-2282-4cdc-8a54-bc2b7d3dcefd" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.leonardodrs.com/role/PensionandOtherPostretirementBenefitsScheduleofPensionPostretirementandSupplementalRetirementPlansDetails" xlink:type="simple" xlink:href="drs-20251231.xsd#PensionandOtherPostretirementBenefitsScheduleofPensionPostretirementandSupplementalRetirementPlansDetails"/>
  <link:definitionLink xlink:role="http://www.leonardodrs.com/role/PensionandOtherPostretirementBenefitsScheduleofPensionPostretirementandSupplementalRetirementPlansDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_d097d848-2921-433f-865a-5f2c0c07cc1b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_42776806-413f-44f8-a8f1-2680a1cc3471" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_d097d848-2921-433f-865a-5f2c0c07cc1b" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_42776806-413f-44f8-a8f1-2680a1cc3471" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_246021e5-3403-4f7e-9aee-75f9795d528b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_42776806-413f-44f8-a8f1-2680a1cc3471" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_246021e5-3403-4f7e-9aee-75f9795d528b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_246021e5-3403-4f7e-9aee-75f9795d528b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_246021e5-3403-4f7e-9aee-75f9795d528b" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_246021e5-3403-4f7e-9aee-75f9795d528b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_6d595354-5999-494d-b7ea-90125a34eb79" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_246021e5-3403-4f7e-9aee-75f9795d528b" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_6d595354-5999-494d-b7ea-90125a34eb79" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionPlansDefinedBenefitMember_a3f3b0a9-ed69-4286-a880-3b74b09546d1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PensionPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_6d595354-5999-494d-b7ea-90125a34eb79" xlink:to="loc_us-gaap_PensionPlansDefinedBenefitMember_a3f3b0a9-ed69-4286-a880-3b74b09546d1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_614642dc-f420-4b0c-a849-7908dedf0c05" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_42776806-413f-44f8-a8f1-2680a1cc3471" xlink:to="loc_srt_CounterpartyNameAxis_614642dc-f420-4b0c-a849-7908dedf0c05" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_614642dc-f420-4b0c-a849-7908dedf0c05_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_614642dc-f420-4b0c-a849-7908dedf0c05" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_614642dc-f420-4b0c-a849-7908dedf0c05_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_d5110d2c-9508-4320-bb78-a8d4b7b33bd5" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_614642dc-f420-4b0c-a849-7908dedf0c05" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_d5110d2c-9508-4320-bb78-a8d4b7b33bd5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_TerminatedVestedParticipantsMember_767d2158-23d6-4f4b-b27f-f284ee1f07db" xlink:href="drs-20251231.xsd#drs_TerminatedVestedParticipantsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_d5110d2c-9508-4320-bb78-a8d4b7b33bd5" xlink:to="loc_drs_TerminatedVestedParticipantsMember_767d2158-23d6-4f4b-b27f-f284ee1f07db" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_83c60d8e-60e0-498e-a56c-6c3a012e7d87" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_d097d848-2921-433f-865a-5f2c0c07cc1b" xlink:to="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_83c60d8e-60e0-498e-a56c-6c3a012e7d87" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanBenefitObligation_c4500b69-4150-48f4-a580-bd5264929590" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanBenefitObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_83c60d8e-60e0-498e-a56c-6c3a012e7d87" xlink:to="loc_us-gaap_DefinedBenefitPlanBenefitObligation_c4500b69-4150-48f4-a580-bd5264929590" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanInterestCost_ffc0ab61-d44d-495a-882a-0dbc7e89f13b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanInterestCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_83c60d8e-60e0-498e-a56c-6c3a012e7d87" xlink:to="loc_us-gaap_DefinedBenefitPlanInterestCost_ffc0ab61-d44d-495a-882a-0dbc7e89f13b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanActuarialGainLoss_6e60c233-f5d1-43e8-81d6-7127678ee5c9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanActuarialGainLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_83c60d8e-60e0-498e-a56c-6c3a012e7d87" xlink:to="loc_us-gaap_DefinedBenefitPlanActuarialGainLoss_6e60c233-f5d1-43e8-81d6-7127678ee5c9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanBenefitObligationBenefitsPaid_dd068e4a-927b-4643-a7dd-58350ffe0916" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanBenefitObligationBenefitsPaid"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward_83c60d8e-60e0-498e-a56c-6c3a012e7d87" xlink:to="loc_us-gaap_DefinedBenefitPlanBenefitObligationBenefitsPaid_dd068e4a-927b-4643-a7dd-58350ffe0916" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanBenefitObligation_0912426d-61de-4ea7-ac13-d10c7d92b96e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanBenefitObligation"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_1efb44fc-ef54-4d30-9b2d-577bb8c6aaf3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_d097d848-2921-433f-865a-5f2c0c07cc1b" xlink:to="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_1efb44fc-ef54-4d30-9b2d-577bb8c6aaf3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_cce8d652-47d1-42ba-b2cd-d2f6c943c4dd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanFairValueOfPlanAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_1efb44fc-ef54-4d30-9b2d-577bb8c6aaf3" xlink:to="loc_us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_cce8d652-47d1-42ba-b2cd-d2f6c943c4dd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets_1d3a530e-a9e5-4dcf-a7fc-6a7e7e092f57" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_1efb44fc-ef54-4d30-9b2d-577bb8c6aaf3" xlink:to="loc_us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets_1d3a530e-a9e5-4dcf-a7fc-6a7e7e092f57" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanContributionsByEmployer_ead0e969-c9f5-4eba-872e-649b6773850b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanContributionsByEmployer"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_1efb44fc-ef54-4d30-9b2d-577bb8c6aaf3" xlink:to="loc_us-gaap_DefinedBenefitPlanContributionsByEmployer_ead0e969-c9f5-4eba-872e-649b6773850b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanPlanAssetsBenefitsPaid_2320a1e4-37a7-4c5e-ab85-e7f23f1ef94e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanPlanAssetsBenefitsPaid"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward_1efb44fc-ef54-4d30-9b2d-577bb8c6aaf3" xlink:to="loc_us-gaap_DefinedBenefitPlanPlanAssetsBenefitsPaid_2320a1e4-37a7-4c5e-ab85-e7f23f1ef94e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_bf70e81e-2aec-40ae-aeed-645c22678715" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanFairValueOfPlanAssets"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanFundedStatusOfPlan_45bfd05c-e43f-4acc-9ed3-b883017b339e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanFundedStatusOfPlan"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_d097d848-2921-433f-865a-5f2c0c07cc1b" xlink:to="loc_us-gaap_DefinedBenefitPlanFundedStatusOfPlan_45bfd05c-e43f-4acc-9ed3-b883017b339e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAssetsTransferredToFromPlan_67bd7965-ac09-49d2-8c1f-aea16440fb0c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanAssetsTransferredToFromPlan"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_d097d848-2921-433f-865a-5f2c0c07cc1b" xlink:to="loc_us-gaap_DefinedBenefitPlanAssetsTransferredToFromPlan_67bd7965-ac09-49d2-8c1f-aea16440fb0c" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.leonardodrs.com/role/PensionandOtherPostretirementBenefitsScheduleofAmountsRecognizedinBalanceSheetDetails" xlink:type="simple" xlink:href="drs-20251231.xsd#PensionandOtherPostretirementBenefitsScheduleofAmountsRecognizedinBalanceSheetDetails"/>
  <link:definitionLink xlink:role="http://www.leonardodrs.com/role/PensionandOtherPostretirementBenefitsScheduleofAmountsRecognizedinBalanceSheetDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_2cacfd6b-629b-4609-8456-188b2914f4c6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_0e95fecb-1014-47ca-bbe3-edcc68c9476c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_2cacfd6b-629b-4609-8456-188b2914f4c6" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_0e95fecb-1014-47ca-bbe3-edcc68c9476c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_1b52351f-f5b9-4a39-8adf-eb89369b8dde" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_0e95fecb-1014-47ca-bbe3-edcc68c9476c" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_1b52351f-f5b9-4a39-8adf-eb89369b8dde" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_1b52351f-f5b9-4a39-8adf-eb89369b8dde_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_1b52351f-f5b9-4a39-8adf-eb89369b8dde" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_1b52351f-f5b9-4a39-8adf-eb89369b8dde_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_b3d51c95-4a9c-40df-ba1e-68f78e7b5ccb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_1b52351f-f5b9-4a39-8adf-eb89369b8dde" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_b3d51c95-4a9c-40df-ba1e-68f78e7b5ccb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionPlansDefinedBenefitMember_3deedf33-8cd9-429c-b50f-cccf49ce4aeb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PensionPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_b3d51c95-4a9c-40df-ba1e-68f78e7b5ccb" xlink:to="loc_us-gaap_PensionPlansDefinedBenefitMember_3deedf33-8cd9-429c-b50f-cccf49ce4aeb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent_dc9298b6-849a-46f1-b997-fb0c30a9bfcf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_2cacfd6b-629b-4609-8456-188b2914f4c6" xlink:to="loc_us-gaap_DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent_dc9298b6-849a-46f1-b997-fb0c30a9bfcf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent_1b410485-dedd-4053-ad1c-38deabecc622" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_2cacfd6b-629b-4609-8456-188b2914f4c6" xlink:to="loc_us-gaap_PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent_1b410485-dedd-4053-ad1c-38deabecc622" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheet_3d85a0f2-d555-417d-aae6-77477d68b62e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_2cacfd6b-629b-4609-8456-188b2914f4c6" xlink:to="loc_us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheet_3d85a0f2-d555-417d-aae6-77477d68b62e" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.leonardodrs.com/role/PensionandOtherPostretirementBenefitsScheduleofAmountsRecognizedInAccumulatedOtherComprehensiveLossBeforeTaxesDetails" xlink:type="simple" xlink:href="drs-20251231.xsd#PensionandOtherPostretirementBenefitsScheduleofAmountsRecognizedInAccumulatedOtherComprehensiveLossBeforeTaxesDetails"/>
  <link:definitionLink xlink:role="http://www.leonardodrs.com/role/PensionandOtherPostretirementBenefitsScheduleofAmountsRecognizedInAccumulatedOtherComprehensiveLossBeforeTaxesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_bec33b98-12e3-4893-90cf-701bed1feb3c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_539122db-eaf4-435a-89ff-d474c2312bcf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_bec33b98-12e3-4893-90cf-701bed1feb3c" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_539122db-eaf4-435a-89ff-d474c2312bcf" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_9b7a45c5-2eae-4c8a-b0ff-7089beb9a0f1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_539122db-eaf4-435a-89ff-d474c2312bcf" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_9b7a45c5-2eae-4c8a-b0ff-7089beb9a0f1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_9b7a45c5-2eae-4c8a-b0ff-7089beb9a0f1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_9b7a45c5-2eae-4c8a-b0ff-7089beb9a0f1" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_9b7a45c5-2eae-4c8a-b0ff-7089beb9a0f1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_b8af274d-0410-47ca-8ea3-13055b020069" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_9b7a45c5-2eae-4c8a-b0ff-7089beb9a0f1" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_b8af274d-0410-47ca-8ea3-13055b020069" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionPlansDefinedBenefitMember_70b65b32-4b96-45c2-b642-a95828fec908" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PensionPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_b8af274d-0410-47ca-8ea3-13055b020069" xlink:to="loc_us-gaap_PensionPlansDefinedBenefitMember_70b65b32-4b96-45c2-b642-a95828fec908" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax_161c12a8-d94c-4677-a084-d56d2c5e000c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_bec33b98-12e3-4893-90cf-701bed1feb3c" xlink:to="loc_us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax_161c12a8-d94c-4677-a084-d56d2c5e000c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTax_12a424ea-4954-4af8-a052-b7416888ed47" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_bec33b98-12e3-4893-90cf-701bed1feb3c" xlink:to="loc_us-gaap_DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTax_12a424ea-4954-4af8-a052-b7416888ed47" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.leonardodrs.com/role/PensionandOtherPostretirementBenefitsScheduleofPensionPlanswithABOandPBOinExcessoftheFairValueofPlanAssetsDetails" xlink:type="simple" xlink:href="drs-20251231.xsd#PensionandOtherPostretirementBenefitsScheduleofPensionPlanswithABOandPBOinExcessoftheFairValueofPlanAssetsDetails"/>
  <link:definitionLink xlink:role="http://www.leonardodrs.com/role/PensionandOtherPostretirementBenefitsScheduleofPensionPlanswithABOandPBOinExcessoftheFairValueofPlanAssetsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_a0cd27a3-ed0d-4a08-92ac-1446ee68a1ce" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_ed5f425f-f424-430d-b33f-0ca8c7f2c316" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_a0cd27a3-ed0d-4a08-92ac-1446ee68a1ce" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_ed5f425f-f424-430d-b33f-0ca8c7f2c316" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_c6636772-e4c0-444c-b90d-83f3f21c9c3c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_ed5f425f-f424-430d-b33f-0ca8c7f2c316" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_c6636772-e4c0-444c-b90d-83f3f21c9c3c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_c6636772-e4c0-444c-b90d-83f3f21c9c3c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_c6636772-e4c0-444c-b90d-83f3f21c9c3c" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_c6636772-e4c0-444c-b90d-83f3f21c9c3c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_42d87909-367b-4660-a34c-8510e447afa9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_c6636772-e4c0-444c-b90d-83f3f21c9c3c" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_42d87909-367b-4660-a34c-8510e447afa9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_PensionPlanAndSupplementalEmployeeRetirementPlanMember_27eb51d6-fe66-4d62-a00f-b8d59c0271d1" xlink:href="drs-20251231.xsd#drs_PensionPlanAndSupplementalEmployeeRetirementPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_42d87909-367b-4660-a34c-8510e447afa9" xlink:to="loc_drs_PensionPlanAndSupplementalEmployeeRetirementPlanMember_27eb51d6-fe66-4d62-a00f-b8d59c0271d1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateProjectedBenefitObligation_feac659e-143e-4fad-8f7f-c7d12340fe55" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateProjectedBenefitObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_a0cd27a3-ed0d-4a08-92ac-1446ee68a1ce" xlink:to="loc_us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateProjectedBenefitObligation_feac659e-143e-4fad-8f7f-c7d12340fe55" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateAccumulatedBenefitObligation_ed28b8b7-0ed4-432c-a451-ba30b8c62c83" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateAccumulatedBenefitObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_a0cd27a3-ed0d-4a08-92ac-1446ee68a1ce" xlink:to="loc_us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateAccumulatedBenefitObligation_ed28b8b7-0ed4-432c-a451-ba30b8c62c83" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateFairValueOfPlanAssets_583798bc-5acb-4edc-9333-00f72c833026" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateFairValueOfPlanAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_a0cd27a3-ed0d-4a08-92ac-1446ee68a1ce" xlink:to="loc_us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateFairValueOfPlanAssets_583798bc-5acb-4edc-9333-00f72c833026" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.leonardodrs.com/role/PensionandOtherPostretirementBenefitsScheduleofWeightedAverageActuarialAssumptionsDetails" xlink:type="simple" xlink:href="drs-20251231.xsd#PensionandOtherPostretirementBenefitsScheduleofWeightedAverageActuarialAssumptionsDetails"/>
  <link:definitionLink xlink:role="http://www.leonardodrs.com/role/PensionandOtherPostretirementBenefitsScheduleofWeightedAverageActuarialAssumptionsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_03a6dd0d-c867-4500-a474-71dfe274532d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_da00b83d-828f-4c55-97b1-db157560a574" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_03a6dd0d-c867-4500-a474-71dfe274532d" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_da00b83d-828f-4c55-97b1-db157560a574" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_ff25588e-e836-4eff-9d51-2c7134d090b2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_da00b83d-828f-4c55-97b1-db157560a574" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_ff25588e-e836-4eff-9d51-2c7134d090b2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_ff25588e-e836-4eff-9d51-2c7134d090b2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_ff25588e-e836-4eff-9d51-2c7134d090b2" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_ff25588e-e836-4eff-9d51-2c7134d090b2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_75666f4a-7f9c-4a83-a265-6b250026c686" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_ff25588e-e836-4eff-9d51-2c7134d090b2" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_75666f4a-7f9c-4a83-a265-6b250026c686" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionPlansDefinedBenefitMember_10cd9703-9af5-4c78-93f3-601f7c652f26" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PensionPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_75666f4a-7f9c-4a83-a265-6b250026c686" xlink:to="loc_us-gaap_PensionPlansDefinedBenefitMember_10cd9703-9af5-4c78-93f3-601f7c652f26" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate_7487ffbb-91e0-4c50-a821-b281694909d6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_03a6dd0d-c867-4500-a474-71dfe274532d" xlink:to="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate_7487ffbb-91e0-4c50-a821-b281694909d6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationExpectedLongTermRateOfReturnOnPlanAssets_7e5e4751-3c58-4b0c-89dc-b8c9942f6c13" xlink:href="drs-20251231.xsd#drs_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationExpectedLongTermRateOfReturnOnPlanAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_03a6dd0d-c867-4500-a474-71dfe274532d" xlink:to="loc_drs_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationExpectedLongTermRateOfReturnOnPlanAssets_7e5e4751-3c58-4b0c-89dc-b8c9942f6c13" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.leonardodrs.com/role/PensionandOtherPostretirementBenefitsScheduleofNetBenefitCostsDetails" xlink:type="simple" xlink:href="drs-20251231.xsd#PensionandOtherPostretirementBenefitsScheduleofNetBenefitCostsDetails"/>
  <link:definitionLink xlink:role="http://www.leonardodrs.com/role/PensionandOtherPostretirementBenefitsScheduleofNetBenefitCostsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_43893c7a-0b59-4790-af6e-a2340509fa73" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_ceb4518c-5d40-458c-a4ab-41a366c9ab45" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_43893c7a-0b59-4790-af6e-a2340509fa73" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_ceb4518c-5d40-458c-a4ab-41a366c9ab45" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_5901f194-e9f0-4489-88e2-3eb372c5c1f7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_ceb4518c-5d40-458c-a4ab-41a366c9ab45" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_5901f194-e9f0-4489-88e2-3eb372c5c1f7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_5901f194-e9f0-4489-88e2-3eb372c5c1f7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_5901f194-e9f0-4489-88e2-3eb372c5c1f7" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_5901f194-e9f0-4489-88e2-3eb372c5c1f7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_ff291aa5-a12b-438c-ae9d-bb31eb0a3eba" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_5901f194-e9f0-4489-88e2-3eb372c5c1f7" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_ff291aa5-a12b-438c-ae9d-bb31eb0a3eba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionPlansDefinedBenefitMember_2ac3b43a-0379-454c-9ce1-1006ec49fd64" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PensionPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_ff291aa5-a12b-438c-ae9d-bb31eb0a3eba" xlink:to="loc_us-gaap_PensionPlansDefinedBenefitMember_2ac3b43a-0379-454c-9ce1-1006ec49fd64" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanInterestCost_5359241a-0674-4971-9227-e21087441657" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanInterestCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_43893c7a-0b59-4790-af6e-a2340509fa73" xlink:to="loc_us-gaap_DefinedBenefitPlanInterestCost_5359241a-0674-4971-9227-e21087441657" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets_11d4e808-db45-48b7-9182-191d36a8c763" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_43893c7a-0b59-4790-af6e-a2340509fa73" xlink:to="loc_us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets_11d4e808-db45-48b7-9182-191d36a8c763" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses_a454afac-1b60-412d-ae27-f31060588d38" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_43893c7a-0b59-4790-af6e-a2340509fa73" xlink:to="loc_us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses_a454afac-1b60-412d-ae27-f31060588d38" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_061b189f-fa2b-493a-8a80-b7dd501e83c3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_43893c7a-0b59-4790-af6e-a2340509fa73" xlink:to="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_061b189f-fa2b-493a-8a80-b7dd501e83c3" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.leonardodrs.com/role/PensionandOtherPostretirementBenefitsScheduleofOtherChangesRecognizedinOtherComprehensiveIncomeDetails" xlink:type="simple" xlink:href="drs-20251231.xsd#PensionandOtherPostretirementBenefitsScheduleofOtherChangesRecognizedinOtherComprehensiveIncomeDetails"/>
  <link:definitionLink xlink:role="http://www.leonardodrs.com/role/PensionandOtherPostretirementBenefitsScheduleofOtherChangesRecognizedinOtherComprehensiveIncomeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_013353f3-b888-4a6b-a319-033b7cc929ae" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_f21ae5c1-0d15-4d44-a713-14e9bf1f9b19" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_013353f3-b888-4a6b-a319-033b7cc929ae" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_f21ae5c1-0d15-4d44-a713-14e9bf1f9b19" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_e35ae6a0-5874-4b1d-9dcb-6648c5c1c180" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_f21ae5c1-0d15-4d44-a713-14e9bf1f9b19" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_e35ae6a0-5874-4b1d-9dcb-6648c5c1c180" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_e35ae6a0-5874-4b1d-9dcb-6648c5c1c180_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_e35ae6a0-5874-4b1d-9dcb-6648c5c1c180" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_e35ae6a0-5874-4b1d-9dcb-6648c5c1c180_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_e5a24d5d-24d1-4f79-8cf5-163361e4f80f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_e35ae6a0-5874-4b1d-9dcb-6648c5c1c180" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_e5a24d5d-24d1-4f79-8cf5-163361e4f80f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionPlansDefinedBenefitMember_b9d2f3d3-83de-483b-b7f8-b2c1fcf04165" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PensionPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_e5a24d5d-24d1-4f79-8cf5-163361e4f80f" xlink:to="loc_us-gaap_PensionPlansDefinedBenefitMember_b9d2f3d3-83de-483b-b7f8-b2c1fcf04165" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansNetUnamortizedGainLossArisingDuringPeriodBeforeTax_4f0290a5-6600-43c1-a754-2fbd4b7ef3d0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansNetUnamortizedGainLossArisingDuringPeriodBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_013353f3-b888-4a6b-a319-033b7cc929ae" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansNetUnamortizedGainLossArisingDuringPeriodBeforeTax_4f0290a5-6600-43c1-a754-2fbd4b7ef3d0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_OtherComprehensiveIncomeLossDefinedBenefitPlanAmortizationOfGainLossesBeforeTax_a035a508-bb91-4a36-b1be-7c5feb7f3b23" xlink:href="drs-20251231.xsd#drs_OtherComprehensiveIncomeLossDefinedBenefitPlanAmortizationOfGainLossesBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_013353f3-b888-4a6b-a319-033b7cc929ae" xlink:to="loc_drs_OtherComprehensiveIncomeLossDefinedBenefitPlanAmortizationOfGainLossesBeforeTax_a035a508-bb91-4a36-b1be-7c5feb7f3b23" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax_72975570-f68f-4646-80fb-27e4db7e8622" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_013353f3-b888-4a6b-a319-033b7cc929ae" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax_72975570-f68f-4646-80fb-27e4db7e8622" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.leonardodrs.com/role/PensionandOtherPostretirementBenefitsScheduleofDefinedBenefitPlanAssumptionsUsedtoCalculateNetPeriodicBenefitCostDetails" xlink:type="simple" xlink:href="drs-20251231.xsd#PensionandOtherPostretirementBenefitsScheduleofDefinedBenefitPlanAssumptionsUsedtoCalculateNetPeriodicBenefitCostDetails"/>
  <link:definitionLink xlink:role="http://www.leonardodrs.com/role/PensionandOtherPostretirementBenefitsScheduleofDefinedBenefitPlanAssumptionsUsedtoCalculateNetPeriodicBenefitCostDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_3d30d91a-7e2d-479e-864c-d43da15050fc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_251cb861-8f61-4d99-afbe-e64290e7bbdb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_3d30d91a-7e2d-479e-864c-d43da15050fc" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_251cb861-8f61-4d99-afbe-e64290e7bbdb" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_e57515ac-9c42-4105-ab94-1093d52850bc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_251cb861-8f61-4d99-afbe-e64290e7bbdb" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_e57515ac-9c42-4105-ab94-1093d52850bc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_e57515ac-9c42-4105-ab94-1093d52850bc_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_e57515ac-9c42-4105-ab94-1093d52850bc" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_e57515ac-9c42-4105-ab94-1093d52850bc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_45110dab-652f-4b4f-aebf-58dfc078515b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_e57515ac-9c42-4105-ab94-1093d52850bc" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_45110dab-652f-4b4f-aebf-58dfc078515b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionPlansDefinedBenefitMember_8b1bed6a-424c-4d54-a099-79be62ac91b4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PensionPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_45110dab-652f-4b4f-aebf-58dfc078515b" xlink:to="loc_us-gaap_PensionPlansDefinedBenefitMember_8b1bed6a-424c-4d54-a099-79be62ac91b4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate_9508fd17-726f-464b-8b51-9afaab5a4117" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_3d30d91a-7e2d-479e-864c-d43da15050fc" xlink:to="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate_9508fd17-726f-464b-8b51-9afaab5a4117" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets_b4b26bbf-4158-4a33-9ca3-a94a3d293cfe" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_3d30d91a-7e2d-479e-864c-d43da15050fc" xlink:to="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets_b4b26bbf-4158-4a33-9ca3-a94a3d293cfe" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.leonardodrs.com/role/PensionandOtherPostretirementBenefitsScheduleofAllocationofPlanAssetsDetails" xlink:type="simple" xlink:href="drs-20251231.xsd#PensionandOtherPostretirementBenefitsScheduleofAllocationofPlanAssetsDetails"/>
  <link:definitionLink xlink:role="http://www.leonardodrs.com/role/PensionandOtherPostretirementBenefitsScheduleofAllocationofPlanAssetsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_1b97769e-180c-4eb1-b940-0aea1919e397" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_e4992c25-2aed-4bf6-a3e3-3e1ee7debfe0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_1b97769e-180c-4eb1-b940-0aea1919e397" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_e4992c25-2aed-4bf6-a3e3-3e1ee7debfe0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis_754f02ea-d0d2-45fd-b763-7b3df954bc33" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_e4992c25-2aed-4bf6-a3e3-3e1ee7debfe0" xlink:to="loc_us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis_754f02ea-d0d2-45fd-b763-7b3df954bc33" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanAssetCategoriesDomain_754f02ea-d0d2-45fd-b763-7b3df954bc33_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PlanAssetCategoriesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis_754f02ea-d0d2-45fd-b763-7b3df954bc33" xlink:to="loc_us-gaap_PlanAssetCategoriesDomain_754f02ea-d0d2-45fd-b763-7b3df954bc33_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanAssetCategoriesDomain_be0e3bcf-d006-402c-8bbe-c41dd83addd2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PlanAssetCategoriesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis_754f02ea-d0d2-45fd-b763-7b3df954bc33" xlink:to="loc_us-gaap_PlanAssetCategoriesDomain_be0e3bcf-d006-402c-8bbe-c41dd83addd2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanEquitySecuritiesMember_8b474ea0-3812-42af-8a04-b41122375030" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanEquitySecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanAssetCategoriesDomain_be0e3bcf-d006-402c-8bbe-c41dd83addd2" xlink:to="loc_us-gaap_DefinedBenefitPlanEquitySecuritiesMember_8b474ea0-3812-42af-8a04-b41122375030" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDebtSecurityMember_66e4c372-f86a-410c-bef7-22fd43dd3c5f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanDebtSecurityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanAssetCategoriesDomain_be0e3bcf-d006-402c-8bbe-c41dd83addd2" xlink:to="loc_us-gaap_DefinedBenefitPlanDebtSecurityMember_66e4c372-f86a-410c-bef7-22fd43dd3c5f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_DefinedBenefitPlanOtherInvestmentMember_65df1624-9ffc-445b-a745-44ee26b0c42a" xlink:href="drs-20251231.xsd#drs_DefinedBenefitPlanOtherInvestmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanAssetCategoriesDomain_be0e3bcf-d006-402c-8bbe-c41dd83addd2" xlink:to="loc_drs_DefinedBenefitPlanOtherInvestmentMember_65df1624-9ffc-445b-a745-44ee26b0c42a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_a923574e-ab69-4820-ae03-24c05362b346" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_e4992c25-2aed-4bf6-a3e3-3e1ee7debfe0" xlink:to="loc_srt_RangeAxis_a923574e-ab69-4820-ae03-24c05362b346" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_a923574e-ab69-4820-ae03-24c05362b346_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_a923574e-ab69-4820-ae03-24c05362b346" xlink:to="loc_srt_RangeMember_a923574e-ab69-4820-ae03-24c05362b346_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_b69153ce-f6bd-473b-9025-bbac34f76736" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_a923574e-ab69-4820-ae03-24c05362b346" xlink:to="loc_srt_RangeMember_b69153ce-f6bd-473b-9025-bbac34f76736" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_a9491d69-f3da-4738-81a5-8b7cd701bf15" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_b69153ce-f6bd-473b-9025-bbac34f76736" xlink:to="loc_srt_MinimumMember_a9491d69-f3da-4738-81a5-8b7cd701bf15" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_9c68133e-a20d-47c9-996f-a4812195bf91" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_b69153ce-f6bd-473b-9025-bbac34f76736" xlink:to="loc_srt_MaximumMember_9c68133e-a20d-47c9-996f-a4812195bf91" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations_2b8dc7ca-33cd-41c2-90e9-abc038d5f9c2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_1b97769e-180c-4eb1-b940-0aea1919e397" xlink:to="loc_us-gaap_DefinedBenefitPlanWeightedAverageAssetAllocations_2b8dc7ca-33cd-41c2-90e9-abc038d5f9c2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanPlanAssetsTargetAllocationPercentage_be2286fb-0508-4c83-ba89-e44b9ed9e095" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanPlanAssetsTargetAllocationPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_1b97769e-180c-4eb1-b940-0aea1919e397" xlink:to="loc_us-gaap_DefinedBenefitPlanPlanAssetsTargetAllocationPercentage_be2286fb-0508-4c83-ba89-e44b9ed9e095" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.leonardodrs.com/role/PensionandOtherPostretirementBenefitsScheduleofFairValueofCategoryofPlanAssetsDetails" xlink:type="simple" xlink:href="drs-20251231.xsd#PensionandOtherPostretirementBenefitsScheduleofFairValueofCategoryofPlanAssetsDetails"/>
  <link:definitionLink xlink:role="http://www.leonardodrs.com/role/PensionandOtherPostretirementBenefitsScheduleofFairValueofCategoryofPlanAssetsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_692d3f83-9ecf-44da-97f0-f3bb65155936" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_86ca6eac-d7de-49cb-a3e1-6246608ab104" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_692d3f83-9ecf-44da-97f0-f3bb65155936" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_86ca6eac-d7de-49cb-a3e1-6246608ab104" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis_9e70cb6f-dfbd-4ba6-b8e4-62b8417aa3b4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_86ca6eac-d7de-49cb-a3e1-6246608ab104" xlink:to="loc_us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis_9e70cb6f-dfbd-4ba6-b8e4-62b8417aa3b4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanAssetCategoriesDomain_9e70cb6f-dfbd-4ba6-b8e4-62b8417aa3b4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PlanAssetCategoriesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis_9e70cb6f-dfbd-4ba6-b8e4-62b8417aa3b4" xlink:to="loc_us-gaap_PlanAssetCategoriesDomain_9e70cb6f-dfbd-4ba6-b8e4-62b8417aa3b4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanAssetCategoriesDomain_b327879b-2c2b-4d75-ad76-52adbf935077" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PlanAssetCategoriesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DefinedBenefitPlanByPlanAssetCategoriesAxis_9e70cb6f-dfbd-4ba6-b8e4-62b8417aa3b4" xlink:to="loc_us-gaap_PlanAssetCategoriesDomain_b327879b-2c2b-4d75-ad76-52adbf935077" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanCashAndCashEquivalentsMember_47cbdfce-efaa-4883-8713-6e2e353ad798" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanCashAndCashEquivalentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanAssetCategoriesDomain_b327879b-2c2b-4d75-ad76-52adbf935077" xlink:to="loc_us-gaap_DefinedBenefitPlanCashAndCashEquivalentsMember_47cbdfce-efaa-4883-8713-6e2e353ad798" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanEquitySecuritiesMember_ed1c6c60-b937-463f-8205-ce23790c20be" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanEquitySecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanAssetCategoriesDomain_b327879b-2c2b-4d75-ad76-52adbf935077" xlink:to="loc_us-gaap_DefinedBenefitPlanEquitySecuritiesMember_ed1c6c60-b937-463f-8205-ce23790c20be" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_DefinedBenefitPlanCollectiveTrustFundsMember_58ab4c37-7260-4f07-90b4-48fbb641c3f4" xlink:href="drs-20251231.xsd#drs_DefinedBenefitPlanCollectiveTrustFundsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanAssetCategoriesDomain_b327879b-2c2b-4d75-ad76-52adbf935077" xlink:to="loc_drs_DefinedBenefitPlanCollectiveTrustFundsMember_58ab4c37-7260-4f07-90b4-48fbb641c3f4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_4ea004e2-534e-4c58-b02f-e87ac0bf6c1a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_86ca6eac-d7de-49cb-a3e1-6246608ab104" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_4ea004e2-534e-4c58-b02f-e87ac0bf6c1a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_4ea004e2-534e-4c58-b02f-e87ac0bf6c1a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_4ea004e2-534e-4c58-b02f-e87ac0bf6c1a" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_4ea004e2-534e-4c58-b02f-e87ac0bf6c1a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_1e93260f-d056-46f7-a131-31a68d57a80b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_4ea004e2-534e-4c58-b02f-e87ac0bf6c1a" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_1e93260f-d056-46f7-a131-31a68d57a80b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel12And3Member_4ffae369-8f2f-49b5-a9b2-3d58d3267a41" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel12And3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_1e93260f-d056-46f7-a131-31a68d57a80b" xlink:to="loc_us-gaap_FairValueInputsLevel12And3Member_4ffae369-8f2f-49b5-a9b2-3d58d3267a41" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_67c6e4fd-74e3-492e-ae35-7be89e337f8b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueInputsLevel12And3Member_4ffae369-8f2f-49b5-a9b2-3d58d3267a41" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_67c6e4fd-74e3-492e-ae35-7be89e337f8b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_5407b3e9-33d7-4cb7-9103-1906396b46f8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueInputsLevel12And3Member_4ffae369-8f2f-49b5-a9b2-3d58d3267a41" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_5407b3e9-33d7-4cb7-9103-1906396b46f8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_20fe7aa4-cb77-43ed-a297-8cf447ae8da9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueInputsLevel12And3Member_4ffae369-8f2f-49b5-a9b2-3d58d3267a41" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_20fe7aa4-cb77-43ed-a297-8cf447ae8da9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_8a1c81a7-bacf-4683-868f-1323cf6f6ee3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_86ca6eac-d7de-49cb-a3e1-6246608ab104" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_8a1c81a7-bacf-4683-868f-1323cf6f6ee3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_8a1c81a7-bacf-4683-868f-1323cf6f6ee3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_8a1c81a7-bacf-4683-868f-1323cf6f6ee3" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_8a1c81a7-bacf-4683-868f-1323cf6f6ee3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_27f8d5f4-6c92-4e99-bb3e-42c446508a13" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_8a1c81a7-bacf-4683-868f-1323cf6f6ee3" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_27f8d5f4-6c92-4e99-bb3e-42c446508a13" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_fcc770c4-0550-4123-adab-bc5abab696e0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_27f8d5f4-6c92-4e99-bb3e-42c446508a13" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_fcc770c4-0550-4123-adab-bc5abab696e0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_324889b4-65e3-4c51-92d0-76d0f51f7e25" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_86ca6eac-d7de-49cb-a3e1-6246608ab104" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_324889b4-65e3-4c51-92d0-76d0f51f7e25" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_324889b4-65e3-4c51-92d0-76d0f51f7e25_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_324889b4-65e3-4c51-92d0-76d0f51f7e25" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_324889b4-65e3-4c51-92d0-76d0f51f7e25_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_e604353b-93e1-4d70-b85d-4a7f5ce9e242" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_324889b4-65e3-4c51-92d0-76d0f51f7e25" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_e604353b-93e1-4d70-b85d-4a7f5ce9e242" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionPlansDefinedBenefitMember_89e9b2f0-f8e7-4c2a-948d-35828b72f7e6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PensionPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_e604353b-93e1-4d70-b85d-4a7f5ce9e242" xlink:to="loc_us-gaap_PensionPlansDefinedBenefitMember_89e9b2f0-f8e7-4c2a-948d-35828b72f7e6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_c1061b61-7fc0-4541-bf21-618c8d7d076a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanFairValueOfPlanAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_692d3f83-9ecf-44da-97f0-f3bb65155936" xlink:to="loc_us-gaap_DefinedBenefitPlanFairValueOfPlanAssets_c1061b61-7fc0-4541-bf21-618c8d7d076a" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.leonardodrs.com/role/PensionandOtherPostretirementBenefitsScheduleofExpectedBenefitPaymentsDetails" xlink:type="simple" xlink:href="drs-20251231.xsd#PensionandOtherPostretirementBenefitsScheduleofExpectedBenefitPaymentsDetails"/>
  <link:definitionLink xlink:role="http://www.leonardodrs.com/role/PensionandOtherPostretirementBenefitsScheduleofExpectedBenefitPaymentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_14c46d4d-193f-4e8b-b01d-0a905325ba76" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_5b34eb12-6353-408b-b43a-6dfe9ef92c9f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_14c46d4d-193f-4e8b-b01d-0a905325ba76" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_5b34eb12-6353-408b-b43a-6dfe9ef92c9f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_ea7a45e6-3645-4e42-8cfd-6ce8ed60235c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_5b34eb12-6353-408b-b43a-6dfe9ef92c9f" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_ea7a45e6-3645-4e42-8cfd-6ce8ed60235c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_ea7a45e6-3645-4e42-8cfd-6ce8ed60235c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_ea7a45e6-3645-4e42-8cfd-6ce8ed60235c" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_ea7a45e6-3645-4e42-8cfd-6ce8ed60235c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_344036bc-57e3-4f80-bc0f-6b579f4f1f01" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_ea7a45e6-3645-4e42-8cfd-6ce8ed60235c" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_344036bc-57e3-4f80-bc0f-6b579f4f1f01" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionPlansDefinedBenefitMember_e4783186-1084-48f4-9f6c-bf48f47eb999" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PensionPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_344036bc-57e3-4f80-bc0f-6b579f4f1f01" xlink:to="loc_us-gaap_PensionPlansDefinedBenefitMember_e4783186-1084-48f4-9f6c-bf48f47eb999" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths_e59a7955-aace-4297-ac51-2a069b4e6bb7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_14c46d4d-193f-4e8b-b01d-0a905325ba76" xlink:to="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths_e59a7955-aace-4297-ac51-2a069b4e6bb7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo_e4cba2bb-bef9-4adb-9900-262fbf79856a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_14c46d4d-193f-4e8b-b01d-0a905325ba76" xlink:to="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo_e4cba2bb-bef9-4adb-9900-262fbf79856a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree_618044f2-fb8d-41c5-8794-4959e948b74f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_14c46d4d-193f-4e8b-b01d-0a905325ba76" xlink:to="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree_618044f2-fb8d-41c5-8794-4959e948b74f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour_a21b347e-c9e3-4c08-ac39-007606984cc3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_14c46d4d-193f-4e8b-b01d-0a905325ba76" xlink:to="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour_a21b347e-c9e3-4c08-ac39-007606984cc3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive_58ec2ee3-baec-4dd3-82d2-b99ce84486ae" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_14c46d4d-193f-4e8b-b01d-0a905325ba76" xlink:to="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive_58ec2ee3-baec-4dd3-82d2-b99ce84486ae" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter_9925c864-673a-47c5-8d91-90df223565f3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_14c46d4d-193f-4e8b-b01d-0a905325ba76" xlink:to="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter_9925c864-673a-47c5-8d91-90df223565f3" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.leonardodrs.com/role/StockbasedCompensationPlansNarrativeDetails" xlink:type="simple" xlink:href="drs-20251231.xsd#StockbasedCompensationPlansNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.leonardodrs.com/role/StockbasedCompensationPlansNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_76709b88-62bb-4aa8-b407-c827a5b6bb34" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_93df142f-a725-430a-a48f-ad29b0dfbbed" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_76709b88-62bb-4aa8-b407-c827a5b6bb34" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_93df142f-a725-430a-a48f-ad29b0dfbbed" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_d9e42f85-8031-443a-87aa-572276665b93" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_93df142f-a725-430a-a48f-ad29b0dfbbed" xlink:to="loc_us-gaap_PlanNameAxis_d9e42f85-8031-443a-87aa-572276665b93" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_d9e42f85-8031-443a-87aa-572276665b93_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_d9e42f85-8031-443a-87aa-572276665b93" xlink:to="loc_us-gaap_PlanNameDomain_d9e42f85-8031-443a-87aa-572276665b93_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_429a65ed-dac3-4405-bbd8-777d1f493f5c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_d9e42f85-8031-443a-87aa-572276665b93" xlink:to="loc_us-gaap_PlanNameDomain_429a65ed-dac3-4405-bbd8-777d1f493f5c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_A2022EquityCompensationPlanMember_981e72f7-d0de-449e-aadf-9297b4eb910d" xlink:href="drs-20251231.xsd#drs_A2022EquityCompensationPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_429a65ed-dac3-4405-bbd8-777d1f493f5c" xlink:to="loc_drs_A2022EquityCompensationPlanMember_981e72f7-d0de-449e-aadf-9297b4eb910d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_A2022LongTermIncentiveProgramMember_20126bcf-0fd0-4cdc-936f-d59ac2420f56" xlink:href="drs-20251231.xsd#drs_A2022LongTermIncentiveProgramMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_429a65ed-dac3-4405-bbd8-777d1f493f5c" xlink:to="loc_drs_A2022LongTermIncentiveProgramMember_20126bcf-0fd0-4cdc-936f-d59ac2420f56" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_EmployeeStockPurchasePlanMember_23dba3ab-52d1-4ab0-907f-57d62038804f" xlink:href="drs-20251231.xsd#drs_EmployeeStockPurchasePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_429a65ed-dac3-4405-bbd8-777d1f493f5c" xlink:to="loc_drs_EmployeeStockPurchasePlanMember_23dba3ab-52d1-4ab0-907f-57d62038804f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_53ba170f-7fdc-4cf0-90b8-883a33399f79" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_93df142f-a725-430a-a48f-ad29b0dfbbed" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_53ba170f-7fdc-4cf0-90b8-883a33399f79" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_53ba170f-7fdc-4cf0-90b8-883a33399f79_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_53ba170f-7fdc-4cf0-90b8-883a33399f79" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_53ba170f-7fdc-4cf0-90b8-883a33399f79_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_3c3520e0-78a8-452e-b1ce-0000aa1afc07" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_53ba170f-7fdc-4cf0-90b8-883a33399f79" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_3c3520e0-78a8-452e-b1ce-0000aa1afc07" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_RADAElectronicIndustriesLtdMember_ed291724-9987-4f6b-991f-844c8d1fd153" xlink:href="drs-20251231.xsd#drs_RADAElectronicIndustriesLtdMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_3c3520e0-78a8-452e-b1ce-0000aa1afc07" xlink:to="loc_drs_RADAElectronicIndustriesLtdMember_ed291724-9987-4f6b-991f-844c8d1fd153" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_5374abfa-1060-4af5-b77a-97f2e31d9770" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_93df142f-a725-430a-a48f-ad29b0dfbbed" xlink:to="loc_us-gaap_AwardTypeAxis_5374abfa-1060-4af5-b77a-97f2e31d9770" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_5374abfa-1060-4af5-b77a-97f2e31d9770_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_5374abfa-1060-4af5-b77a-97f2e31d9770" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_5374abfa-1060-4af5-b77a-97f2e31d9770_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_f72394e4-5f9a-43f2-8cde-ae983cc4bf65" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_5374abfa-1060-4af5-b77a-97f2e31d9770" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_f72394e4-5f9a-43f2-8cde-ae983cc4bf65" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_990ceead-480a-4619-8a39-64ee9de05f7b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_f72394e4-5f9a-43f2-8cde-ae983cc4bf65" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_990ceead-480a-4619-8a39-64ee9de05f7b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_PerformanceBasedRestrictedStockUnitMember_b4e1bcff-f236-4f76-9189-0dbc5ed24674" xlink:href="drs-20251231.xsd#drs_PerformanceBasedRestrictedStockUnitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_f72394e4-5f9a-43f2-8cde-ae983cc4bf65" xlink:to="loc_drs_PerformanceBasedRestrictedStockUnitMember_b4e1bcff-f236-4f76-9189-0dbc5ed24674" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_9e366402-8c53-4901-a747-ed0b40730102" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_f72394e4-5f9a-43f2-8cde-ae983cc4bf65" xlink:to="loc_us-gaap_EmployeeStockOptionMember_9e366402-8c53-4901-a747-ed0b40730102" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized_651cbd51-7222-42d0-9703-d7e416fa22e2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_76709b88-62bb-4aa8-b407-c827a5b6bb34" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized_651cbd51-7222-42d0-9703-d7e416fa22e2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_b64894ed-6eea-4f9f-b172-c875db9598ca" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockCapitalSharesReservedForFutureIssuance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_76709b88-62bb-4aa8-b407-c827a5b6bb34" xlink:to="loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_b64894ed-6eea-4f9f-b172-c875db9598ca" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAssumedThroughAcquisition_7d6d390e-290a-48be-82ae-12e909e762e1" xlink:href="drs-20251231.xsd#drs_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAssumedThroughAcquisition"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_76709b88-62bb-4aa8-b407-c827a5b6bb34" xlink:to="loc_drs_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAssumedThroughAcquisition_7d6d390e-290a-48be-82ae-12e909e762e1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAssumedThroughAcquisitionExercisableTerm_8dfc3c36-a87b-401a-ac6d-013f0d23a929" xlink:href="drs-20251231.xsd#drs_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAssumedThroughAcquisitionExercisableTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_76709b88-62bb-4aa8-b407-c827a5b6bb34" xlink:to="loc_drs_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAssumedThroughAcquisitionExercisableTerm_8dfc3c36-a87b-401a-ac6d-013f0d23a929" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_e65a2ece-0b6e-42d1-9956-79ed3b9783db" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_76709b88-62bb-4aa8-b407-c827a5b6bb34" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_e65a2ece-0b6e-42d1-9956-79ed3b9783db" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfFinancialMetrics_90cde37c-cc95-4dfd-827b-e129259277c4" xlink:href="drs-20251231.xsd#drs_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfFinancialMetrics"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_76709b88-62bb-4aa8-b407-c827a5b6bb34" xlink:to="loc_drs_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfFinancialMetrics_90cde37c-cc95-4dfd-827b-e129259277c4" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardDiscountFromMarketPricePurchaseDate_af79131b-42c0-495e-8993-fa2e8f284eb1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardDiscountFromMarketPricePurchaseDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_76709b88-62bb-4aa8-b407-c827a5b6bb34" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardDiscountFromMarketPricePurchaseDate_af79131b-42c0-495e-8993-fa2e8f284eb1" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_019b9f4e-c463-72d5-89aa-4aeeeb2bee2b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_76709b88-62bb-4aa8-b407-c827a5b6bb34" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_019b9f4e-c463-72d5-89aa-4aeeeb2bee2b" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions_ce7d2e14-8caf-4ce4-bc0b-5565212b2fa0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_76709b88-62bb-4aa8-b407-c827a5b6bb34" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions_ce7d2e14-8caf-4ce4-bc0b-5565212b2fa0" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_d1b6761b-32ba-4d3d-b2e8-bf6873383dd4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_76709b88-62bb-4aa8-b407-c827a5b6bb34" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_d1b6761b-32ba-4d3d-b2e8-bf6873383dd4" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_fe01afb8-87e0-4eb9-9761-ca436f1c9897" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_76709b88-62bb-4aa8-b407-c827a5b6bb34" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_fe01afb8-87e0-4eb9-9761-ca436f1c9897" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_2b5febd7-b396-425b-b11f-6256b9c6e1ab" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_76709b88-62bb-4aa8-b407-c827a5b6bb34" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_2b5febd7-b396-425b-b11f-6256b9c6e1ab" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue_7dacc4e8-2681-4fba-a7bb-0682404195fa" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_76709b88-62bb-4aa8-b407-c827a5b6bb34" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue_7dacc4e8-2681-4fba-a7bb-0682404195fa" xlink:type="arc" order="12"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.leonardodrs.com/role/StockbasedCompensationPlansScheduleofRSUsActivityDetails" xlink:type="simple" xlink:href="drs-20251231.xsd#StockbasedCompensationPlansScheduleofRSUsActivityDetails"/>
  <link:definitionLink xlink:role="http://www.leonardodrs.com/role/StockbasedCompensationPlansScheduleofRSUsActivityDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c0aaa74b-8667-41e6-bd77-97708a8cb5d8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_c78b8325-73ee-42d3-8483-e7db500789a4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c0aaa74b-8667-41e6-bd77-97708a8cb5d8" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_c78b8325-73ee-42d3-8483-e7db500789a4" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_4b959e6d-924c-4fd5-b663-42912ffe2f76" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_c78b8325-73ee-42d3-8483-e7db500789a4" xlink:to="loc_us-gaap_AwardTypeAxis_4b959e6d-924c-4fd5-b663-42912ffe2f76" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_4b959e6d-924c-4fd5-b663-42912ffe2f76_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_4b959e6d-924c-4fd5-b663-42912ffe2f76" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_4b959e6d-924c-4fd5-b663-42912ffe2f76_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_54938da4-7974-4b2b-a9e9-8c02f6d86c47" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_4b959e6d-924c-4fd5-b663-42912ffe2f76" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_54938da4-7974-4b2b-a9e9-8c02f6d86c47" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_69c13e3e-7354-4b1f-8124-20e1e06bdd3e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_54938da4-7974-4b2b-a9e9-8c02f6d86c47" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_69c13e3e-7354-4b1f-8124-20e1e06bdd3e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_56cf06b9-b56a-4ed4-a1d0-d77464a463e6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c0aaa74b-8667-41e6-bd77-97708a8cb5d8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_56cf06b9-b56a-4ed4-a1d0-d77464a463e6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_dd5e0f10-bd40-4afc-85d4-5e86916a18d3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_56cf06b9-b56a-4ed4-a1d0-d77464a463e6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_dd5e0f10-bd40-4afc-85d4-5e86916a18d3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_5e2db743-ddc2-4411-a49d-aa957deaaf87" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_56cf06b9-b56a-4ed4-a1d0-d77464a463e6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_5e2db743-ddc2-4411-a49d-aa957deaaf87" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_db40e703-64be-40ba-9c32-2f605305a36a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_56cf06b9-b56a-4ed4-a1d0-d77464a463e6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_db40e703-64be-40ba-9c32-2f605305a36a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_697b433e-a54d-4b4e-8fd0-be05c04b1772" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_56cf06b9-b56a-4ed4-a1d0-d77464a463e6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_697b433e-a54d-4b4e-8fd0-be05c04b1772" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_9893c3d2-648d-40d7-8dab-79836c8d2136" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_96e4011b-8889-4659-8ee1-2a2a16cafec9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c0aaa74b-8667-41e6-bd77-97708a8cb5d8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_96e4011b-8889-4659-8ee1-2a2a16cafec9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_91736429-b454-49e9-8fb7-06afda64237e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_96e4011b-8889-4659-8ee1-2a2a16cafec9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_91736429-b454-49e9-8fb7-06afda64237e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_a620fd47-879c-4502-9318-fd20cbf817d8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_96e4011b-8889-4659-8ee1-2a2a16cafec9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_a620fd47-879c-4502-9318-fd20cbf817d8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_3cfb19d4-c2c8-4c94-adc7-53db3958eec7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_96e4011b-8889-4659-8ee1-2a2a16cafec9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_3cfb19d4-c2c8-4c94-adc7-53db3958eec7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_57511145-433a-4076-83eb-2c60893a5071" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_96e4011b-8889-4659-8ee1-2a2a16cafec9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_57511145-433a-4076-83eb-2c60893a5071" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_561bf30b-496b-4783-bb26-a6478d33dcf2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.leonardodrs.com/role/StockbasedCompensationPlansScheduleofPRSUsActivityDetails" xlink:type="simple" xlink:href="drs-20251231.xsd#StockbasedCompensationPlansScheduleofPRSUsActivityDetails"/>
  <link:definitionLink xlink:role="http://www.leonardodrs.com/role/StockbasedCompensationPlansScheduleofPRSUsActivityDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_6906858f-528d-4edc-a804-861979068ba5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_166c33d3-4193-49ec-a58d-8f3b60d10546" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_6906858f-528d-4edc-a804-861979068ba5" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_166c33d3-4193-49ec-a58d-8f3b60d10546" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_09ea60e5-ded8-47d6-9fc1-9d8c133d1840" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_166c33d3-4193-49ec-a58d-8f3b60d10546" xlink:to="loc_us-gaap_AwardTypeAxis_09ea60e5-ded8-47d6-9fc1-9d8c133d1840" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_09ea60e5-ded8-47d6-9fc1-9d8c133d1840_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_09ea60e5-ded8-47d6-9fc1-9d8c133d1840" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_09ea60e5-ded8-47d6-9fc1-9d8c133d1840_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_d70b42a4-341a-4c08-9757-bcb556c83362" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_09ea60e5-ded8-47d6-9fc1-9d8c133d1840" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_d70b42a4-341a-4c08-9757-bcb556c83362" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_PerformanceBasedRestrictedStockUnitMember_557237c2-7574-4e94-b6ac-bbdaeccf685d" xlink:href="drs-20251231.xsd#drs_PerformanceBasedRestrictedStockUnitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_d70b42a4-341a-4c08-9757-bcb556c83362" xlink:to="loc_drs_PerformanceBasedRestrictedStockUnitMember_557237c2-7574-4e94-b6ac-bbdaeccf685d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_fcaa1140-919c-47fb-b0da-8b285f4210af" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_6906858f-528d-4edc-a804-861979068ba5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_fcaa1140-919c-47fb-b0da-8b285f4210af" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_a3bb836b-35d7-4873-9426-de83854e596f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_fcaa1140-919c-47fb-b0da-8b285f4210af" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_a3bb836b-35d7-4873-9426-de83854e596f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_0edbb37f-4609-4ce9-81e9-73c485da0c6a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_fcaa1140-919c-47fb-b0da-8b285f4210af" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_0edbb37f-4609-4ce9-81e9-73c485da0c6a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_749037cf-63d2-4c07-954d-b4d3840573c3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_fcaa1140-919c-47fb-b0da-8b285f4210af" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_749037cf-63d2-4c07-954d-b4d3840573c3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_460aba13-7c38-489a-9d0c-4b8251d25450" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_fcaa1140-919c-47fb-b0da-8b285f4210af" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_460aba13-7c38-489a-9d0c-4b8251d25450" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsPerformanceAdjustmentsInPeriod_019c4bc6-8abb-7608-9a2f-5d220a13c701" xlink:href="drs-20251231.xsd#drs_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsPerformanceAdjustmentsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_fcaa1140-919c-47fb-b0da-8b285f4210af" xlink:to="loc_drs_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsPerformanceAdjustmentsInPeriod_019c4bc6-8abb-7608-9a2f-5d220a13c701" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_9daf79ca-6862-4c54-a204-ff43011d8ade" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_49c3ffa0-42c0-4258-a9b4-2c637f8ea797" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_6906858f-528d-4edc-a804-861979068ba5" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_49c3ffa0-42c0-4258-a9b4-2c637f8ea797" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_8e86c0e5-abb0-4867-a910-042ce6e045cf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_49c3ffa0-42c0-4258-a9b4-2c637f8ea797" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_8e86c0e5-abb0-4867-a910-042ce6e045cf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_88d1b591-10cc-45db-9b93-77175999d05a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_49c3ffa0-42c0-4258-a9b4-2c637f8ea797" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_88d1b591-10cc-45db-9b93-77175999d05a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_ecacbd50-0d9e-4390-b70d-93e8888253e7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_49c3ffa0-42c0-4258-a9b4-2c637f8ea797" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_ecacbd50-0d9e-4390-b70d-93e8888253e7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_fd8eba67-88dc-4ac2-b00a-27d972ff51c7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_49c3ffa0-42c0-4258-a9b4-2c637f8ea797" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_fd8eba67-88dc-4ac2-b00a-27d972ff51c7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsPerformanceAdjustmentsWeightedAverageGrantDateFairValue_019c4bc6-8abb-7538-ae72-a89adbbb1168" xlink:href="drs-20251231.xsd#drs_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsPerformanceAdjustmentsWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_49c3ffa0-42c0-4258-a9b4-2c637f8ea797" xlink:to="loc_drs_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsPerformanceAdjustmentsWeightedAverageGrantDateFairValue_019c4bc6-8abb-7538-ae72-a89adbbb1168" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_5c0a92b1-b24e-418d-9a7b-0a031fe83333" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.leonardodrs.com/role/StockbasedCompensationPlansScheduleofPRSUsValuationAssumptionsDetails" xlink:type="simple" xlink:href="drs-20251231.xsd#StockbasedCompensationPlansScheduleofPRSUsValuationAssumptionsDetails"/>
  <link:definitionLink xlink:role="http://www.leonardodrs.com/role/StockbasedCompensationPlansScheduleofPRSUsValuationAssumptionsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_17c59403-319d-4849-ac09-ced586b27416" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_c714b603-804a-482a-a985-eac5d2b962a7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_17c59403-319d-4849-ac09-ced586b27416" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_c714b603-804a-482a-a985-eac5d2b962a7" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_d9fbcbea-bcfb-483f-84e1-e807ab3f59ae" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_c714b603-804a-482a-a985-eac5d2b962a7" xlink:to="loc_us-gaap_AwardTypeAxis_d9fbcbea-bcfb-483f-84e1-e807ab3f59ae" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_d9fbcbea-bcfb-483f-84e1-e807ab3f59ae_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_d9fbcbea-bcfb-483f-84e1-e807ab3f59ae" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_d9fbcbea-bcfb-483f-84e1-e807ab3f59ae_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_25430bf2-516e-48ae-b9ed-1f7f1aac953b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_d9fbcbea-bcfb-483f-84e1-e807ab3f59ae" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_25430bf2-516e-48ae-b9ed-1f7f1aac953b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_PerformanceBasedRestrictedStockUnitMember_1e13c5de-414e-4509-aa38-769461243cae" xlink:href="drs-20251231.xsd#drs_PerformanceBasedRestrictedStockUnitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_25430bf2-516e-48ae-b9ed-1f7f1aac953b" xlink:to="loc_drs_PerformanceBasedRestrictedStockUnitMember_1e13c5de-414e-4509-aa38-769461243cae" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsGrantDateStockPrice_fdbd68c0-824c-41e8-9219-88b674851d29" xlink:href="drs-20251231.xsd#drs_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsGrantDateStockPrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_17c59403-319d-4849-ac09-ced586b27416" xlink:to="loc_drs_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsGrantDateStockPrice_fdbd68c0-824c-41e8-9219-88b674851d29" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_e0a7508e-a540-444a-a49f-c229cfe4edbf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_17c59403-319d-4849-ac09-ced586b27416" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_e0a7508e-a540-444a-a49f-c229cfe4edbf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_8f7d49aa-ac26-412d-978e-93a735d4d276" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_17c59403-319d-4849-ac09-ced586b27416" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_8f7d49aa-ac26-412d-978e-93a735d4d276" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_b49b1581-ae49-4d2d-a798-6c144638ac52" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_17c59403-319d-4849-ac09-ced586b27416" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_b49b1581-ae49-4d2d-a798-6c144638ac52" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.leonardodrs.com/role/EarningsPerShareStockRepurchasesandDividendsNarrativeDetails" xlink:type="simple" xlink:href="drs-20251231.xsd#EarningsPerShareStockRepurchasesandDividendsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.leonardodrs.com/role/EarningsPerShareStockRepurchasesandDividendsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_96d4103e-af1a-4ad8-a574-509c7159a339" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEarningsPerShareBasicByCommonClassTable_1dfcfec1-5318-4cc1-9951-b64cd999500d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfEarningsPerShareBasicByCommonClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_96d4103e-af1a-4ad8-a574-509c7159a339" xlink:to="loc_us-gaap_ScheduleOfEarningsPerShareBasicByCommonClassTable_1dfcfec1-5318-4cc1-9951-b64cd999500d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_4a5630f8-8927-4785-8382-d052fd2a7fb0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEarningsPerShareBasicByCommonClassTable_1dfcfec1-5318-4cc1-9951-b64cd999500d" xlink:to="loc_us-gaap_StatementClassOfStockAxis_4a5630f8-8927-4785-8382-d052fd2a7fb0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_4a5630f8-8927-4785-8382-d052fd2a7fb0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_4a5630f8-8927-4785-8382-d052fd2a7fb0" xlink:to="loc_us-gaap_ClassOfStockDomain_4a5630f8-8927-4785-8382-d052fd2a7fb0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_b6cdceb5-52a8-44d8-b02e-008e83d2ef1f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_4a5630f8-8927-4785-8382-d052fd2a7fb0" xlink:to="loc_us-gaap_ClassOfStockDomain_b6cdceb5-52a8-44d8-b02e-008e83d2ef1f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonClassAMember_2b1f0cba-debb-4e90-9df2-9f59c115891f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonClassAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_b6cdceb5-52a8-44d8-b02e-008e83d2ef1f" xlink:to="loc_us-gaap_CommonClassAMember_2b1f0cba-debb-4e90-9df2-9f59c115891f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_833821ba-9026-4b08-ae64-ab3fe91537c6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEarningsPerShareBasicByCommonClassTable_1dfcfec1-5318-4cc1-9951-b64cd999500d" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_833821ba-9026-4b08-ae64-ab3fe91537c6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_833821ba-9026-4b08-ae64-ab3fe91537c6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_833821ba-9026-4b08-ae64-ab3fe91537c6" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_833821ba-9026-4b08-ae64-ab3fe91537c6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_3cb8baad-181d-44ca-958a-abd5fc34a395" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_833821ba-9026-4b08-ae64-ab3fe91537c6" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_3cb8baad-181d-44ca-958a-abd5fc34a395" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_153bca34-9033-4a69-b205-e2f51377e61b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_3cb8baad-181d-44ca-958a-abd5fc34a395" xlink:to="loc_us-gaap_SubsequentEventMember_153bca34-9033-4a69-b205-e2f51377e61b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementScenarioAxis_019c65a8-2aea-7dab-947c-714a942c7823" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StatementScenarioAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEarningsPerShareBasicByCommonClassTable_1dfcfec1-5318-4cc1-9951-b64cd999500d" xlink:to="loc_srt_StatementScenarioAxis_019c65a8-2aea-7dab-947c-714a942c7823" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_019c65a8-2aea-7dab-947c-714a942c7823_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementScenarioAxis_019c65a8-2aea-7dab-947c-714a942c7823" xlink:to="loc_srt_ScenarioUnspecifiedDomain_019c65a8-2aea-7dab-947c-714a942c7823_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_019c65a8-2aea-7e2f-9af1-883755a810e8" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementScenarioAxis_019c65a8-2aea-7dab-947c-714a942c7823" xlink:to="loc_srt_ScenarioUnspecifiedDomain_019c65a8-2aea-7e2f-9af1-883755a810e8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioForecastMember_019c65a8-5d1f-7bf9-bfef-555d27d3c668" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ScenarioForecastMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ScenarioUnspecifiedDomain_019c65a8-2aea-7e2f-9af1-883755a810e8" xlink:to="loc_srt_ScenarioForecastMember_019c65a8-5d1f-7bf9-bfef-555d27d3c668" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StockRepurchaseProgramAuthorizedAmount1_0652601e-a84b-4107-803f-ec1b0b0311b6" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StockRepurchaseProgramAuthorizedAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_96d4103e-af1a-4ad8-a574-509c7159a339" xlink:to="loc_srt_StockRepurchaseProgramAuthorizedAmount1_0652601e-a84b-4107-803f-ec1b0b0311b6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodValue_c6a317e2-606b-4699-8bbb-b0383b618a43" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockRepurchasedAndRetiredDuringPeriodValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_96d4103e-af1a-4ad8-a574-509c7159a339" xlink:to="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodValue_c6a317e2-606b-4699-8bbb-b0383b618a43" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockDividendsPerShareDeclared_f56a1c3b-78a9-40d3-aa28-fb7c9bc14fab" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockDividendsPerShareDeclared"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodValue_c6a317e2-606b-4699-8bbb-b0383b618a43" xlink:to="loc_us-gaap_CommonStockDividendsPerShareDeclared_f56a1c3b-78a9-40d3-aa28-fb7c9bc14fab" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.leonardodrs.com/role/CommitmentsandContingenciesNarrativeDetails" xlink:type="simple" xlink:href="drs-20251231.xsd#CommitmentsandContingenciesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.leonardodrs.com/role/CommitmentsandContingenciesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProductWarrantyLiabilityLineItems_3fbde0e3-5afd-49fb-802d-857aca8eb719" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProductWarrantyLiabilityLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProductWarrantyLiabilityTable_78d4a0b0-1038-48e6-b5ab-84230e039647" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProductWarrantyLiabilityTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ProductWarrantyLiabilityLineItems_3fbde0e3-5afd-49fb-802d-857aca8eb719" xlink:to="loc_us-gaap_ProductWarrantyLiabilityTable_78d4a0b0-1038-48e6-b5ab-84230e039647" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_34cc178d-5a9a-4833-b010-6a0f13f2bdfa" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ProductWarrantyLiabilityTable_78d4a0b0-1038-48e6-b5ab-84230e039647" xlink:to="loc_srt_RangeAxis_34cc178d-5a9a-4833-b010-6a0f13f2bdfa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_34cc178d-5a9a-4833-b010-6a0f13f2bdfa_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_34cc178d-5a9a-4833-b010-6a0f13f2bdfa" xlink:to="loc_srt_RangeMember_34cc178d-5a9a-4833-b010-6a0f13f2bdfa_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_9f3d7b8e-8023-4b07-a69b-2a57bd09986d" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_34cc178d-5a9a-4833-b010-6a0f13f2bdfa" xlink:to="loc_srt_RangeMember_9f3d7b8e-8023-4b07-a69b-2a57bd09986d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_9361e859-032e-46ec-84e6-bea1ead4f598" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_9f3d7b8e-8023-4b07-a69b-2a57bd09986d" xlink:to="loc_srt_MinimumMember_9361e859-032e-46ec-84e6-bea1ead4f598" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_eb636c91-205b-4356-a6ec-e029cf2c94a0" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_9f3d7b8e-8023-4b07-a69b-2a57bd09986d" xlink:to="loc_srt_MaximumMember_eb636c91-205b-4356-a6ec-e029cf2c94a0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCharges_fbbaebf2-ee82-4c3b-ae19-c6ef40c52c09" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductWarrantyLiabilityLineItems_3fbde0e3-5afd-49fb-802d-857aca8eb719" xlink:to="loc_us-gaap_RestructuringCharges_fbbaebf2-ee82-4c3b-ae19-c6ef40c52c09" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_StandardProductWarrantyTerm_7e40af30-475d-4038-b81f-332fc7b48b28" xlink:href="drs-20251231.xsd#drs_StandardProductWarrantyTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductWarrantyLiabilityLineItems_3fbde0e3-5afd-49fb-802d-857aca8eb719" xlink:to="loc_drs_StandardProductWarrantyTerm_7e40af30-475d-4038-b81f-332fc7b48b28" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.leonardodrs.com/role/CommitmentsandContingenciesScheduleofRestructuringCostsincurredbySegmentandbyNatureofCostincurredDetails" xlink:type="simple" xlink:href="drs-20251231.xsd#CommitmentsandContingenciesScheduleofRestructuringCostsincurredbySegmentandbyNatureofCostincurredDetails"/>
  <link:definitionLink xlink:role="http://www.leonardodrs.com/role/CommitmentsandContingenciesScheduleofRestructuringCostsincurredbySegmentandbyNatureofCostincurredDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_b20b7169-a1d2-4658-95ff-1339254e1f79" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringCostAndReserveLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_40894d7a-c196-483c-a119-a0eb051a5067" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_b20b7169-a1d2-4658-95ff-1339254e1f79" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_40894d7a-c196-483c-a119-a0eb051a5067" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveAxis_61e9b44f-a256-45a6-a33b-ff7c759ff6f9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringCostAndReserveAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_40894d7a-c196-483c-a119-a0eb051a5067" xlink:to="loc_us-gaap_RestructuringCostAndReserveAxis_61e9b44f-a256-45a6-a33b-ff7c759ff6f9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_61e9b44f-a256-45a6-a33b-ff7c759ff6f9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_61e9b44f-a256-45a6-a33b-ff7c759ff6f9" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_61e9b44f-a256-45a6-a33b-ff7c759ff6f9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_e3796722-7c23-475f-a4e7-65768a4cbaeb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_61e9b44f-a256-45a6-a33b-ff7c759ff6f9" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_e3796722-7c23-475f-a4e7-65768a4cbaeb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeSeveranceMember_10f25a52-f47b-4e90-8b39-65b241abff3f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeSeveranceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_e3796722-7c23-475f-a4e7-65768a4cbaeb" xlink:to="loc_us-gaap_EmployeeSeveranceMember_10f25a52-f47b-4e90-8b39-65b241abff3f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FacilityClosingMember_1aed23b7-05cc-46fe-b2e8-b2e299d3428d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FacilityClosingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_e3796722-7c23-475f-a4e7-65768a4cbaeb" xlink:to="loc_us-gaap_FacilityClosingMember_1aed23b7-05cc-46fe-b2e8-b2e299d3428d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_75ff3fd7-5df7-45e8-b14b-435b1ac6b830" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_40894d7a-c196-483c-a119-a0eb051a5067" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_75ff3fd7-5df7-45e8-b14b-435b1ac6b830" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_75ff3fd7-5df7-45e8-b14b-435b1ac6b830_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_75ff3fd7-5df7-45e8-b14b-435b1ac6b830" xlink:to="loc_us-gaap_SegmentDomain_75ff3fd7-5df7-45e8-b14b-435b1ac6b830_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_a767f890-aea6-41f9-b909-7b29f79684c9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_75ff3fd7-5df7-45e8-b14b-435b1ac6b830" xlink:to="loc_us-gaap_SegmentDomain_a767f890-aea6-41f9-b909-7b29f79684c9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_AdvancedSensingAndComputingSegmentMember_54cf0a00-38fc-4220-8b2b-13c0e550855c" xlink:href="drs-20251231.xsd#drs_AdvancedSensingAndComputingSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_a767f890-aea6-41f9-b909-7b29f79684c9" xlink:to="loc_drs_AdvancedSensingAndComputingSegmentMember_54cf0a00-38fc-4220-8b2b-13c0e550855c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_2e2f5601-d967-4679-be44-504a6d44b7f8" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_40894d7a-c196-483c-a119-a0eb051a5067" xlink:to="loc_srt_ConsolidationItemsAxis_2e2f5601-d967-4679-be44-504a6d44b7f8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_2e2f5601-d967-4679-be44-504a6d44b7f8_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_2e2f5601-d967-4679-be44-504a6d44b7f8" xlink:to="loc_srt_ConsolidationItemsDomain_2e2f5601-d967-4679-be44-504a6d44b7f8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_2b2ce951-faa1-4598-863e-2b77b0d1c907" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_2e2f5601-d967-4679-be44-504a6d44b7f8" xlink:to="loc_srt_ConsolidationItemsDomain_2b2ce951-faa1-4598-863e-2b77b0d1c907" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_aa56ac09-872e-494d-bf69-b38b4838a33f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_2b2ce951-faa1-4598-863e-2b77b0d1c907" xlink:to="loc_us-gaap_OperatingSegmentsMember_aa56ac09-872e-494d-bf69-b38b4838a33f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCharges_d9c37334-969c-440a-9d38-2359c8514bf4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_b20b7169-a1d2-4658-95ff-1339254e1f79" xlink:to="loc_us-gaap_RestructuringCharges_d9c37334-969c-440a-9d38-2359c8514bf4" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.leonardodrs.com/role/RelatedPartyTransactionsDetails" xlink:type="simple" xlink:href="drs-20251231.xsd#RelatedPartyTransactionsDetails"/>
  <link:definitionLink xlink:role="http://www.leonardodrs.com/role/RelatedPartyTransactionsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionLineItems_820b97dc-6442-4dd1-bb2a-ffe6447ec4e8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RelatedPartyTransactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_5d23b61d-3193-4848-a67d-65f82c577849" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_820b97dc-6442-4dd1-bb2a-ffe6447ec4e8" xlink:to="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_5d23b61d-3193-4848-a67d-65f82c577849" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_41ceb90b-b7cb-4e56-afcf-a3f5db2efb2d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_5d23b61d-3193-4848-a67d-65f82c577849" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_41ceb90b-b7cb-4e56-afcf-a3f5db2efb2d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_41ceb90b-b7cb-4e56-afcf-a3f5db2efb2d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_41ceb90b-b7cb-4e56-afcf-a3f5db2efb2d" xlink:to="loc_us-gaap_RelatedPartyDomain_41ceb90b-b7cb-4e56-afcf-a3f5db2efb2d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_dc2e94ac-dc87-4553-be8c-b9101e5e96ae" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_41ceb90b-b7cb-4e56-afcf-a3f5db2efb2d" xlink:to="loc_us-gaap_RelatedPartyDomain_dc2e94ac-dc87-4553-be8c-b9101e5e96ae" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyMember_cd8fd2a9-818d-48d0-af0c-75455caed3c8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RelatedPartyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_dc2e94ac-dc87-4553-be8c-b9101e5e96ae" xlink:to="loc_us-gaap_RelatedPartyMember_cd8fd2a9-818d-48d0-af0c-75455caed3c8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_1ac340ac-4adb-46b4-b3b7-f85526ce2e0f" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_5d23b61d-3193-4848-a67d-65f82c577849" xlink:to="loc_srt_CounterpartyNameAxis_1ac340ac-4adb-46b4-b3b7-f85526ce2e0f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_1ac340ac-4adb-46b4-b3b7-f85526ce2e0f_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_1ac340ac-4adb-46b4-b3b7-f85526ce2e0f" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_1ac340ac-4adb-46b4-b3b7-f85526ce2e0f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_e4f3e03e-555e-4b95-9dbf-6947750dbb29" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_1ac340ac-4adb-46b4-b3b7-f85526ce2e0f" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_e4f3e03e-555e-4b95-9dbf-6947750dbb29" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_LeonardoSpAMember_039119c9-e138-4d06-8367-2d04f43dfd96" xlink:href="drs-20251231.xsd#drs_LeonardoSpAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_e4f3e03e-555e-4b95-9dbf-6947750dbb29" xlink:to="loc_drs_LeonardoSpAMember_039119c9-e138-4d06-8367-2d04f43dfd96" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_UnnamedPrivateCompanyMember_445d1231-5c50-4dcf-a776-96b20767c32c" xlink:href="drs-20251231.xsd#drs_UnnamedPrivateCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_e4f3e03e-555e-4b95-9dbf-6947750dbb29" xlink:to="loc_drs_UnnamedPrivateCompanyMember_445d1231-5c50-4dcf-a776-96b20767c32c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_05d6af7c-6fe7-4be9-86cf-778d278755e3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_820b97dc-6442-4dd1-bb2a-ffe6447ec4e8" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_05d6af7c-6fe7-4be9-86cf-778d278755e3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfRevenue_aaebf30e-49d4-4d39-8627-fa6a25f2d0a2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CostOfRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_820b97dc-6442-4dd1-bb2a-ffe6447ec4e8" xlink:to="loc_us-gaap_CostOfRevenue_aaebf30e-49d4-4d39-8627-fa6a25f2d0a2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableNetCurrent_5303f1f7-f8fa-419e-a54e-9e91282b7133" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccountsReceivableNetCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_820b97dc-6442-4dd1-bb2a-ffe6447ec4e8" xlink:to="loc_us-gaap_AccountsReceivableNetCurrent_5303f1f7-f8fa-419e-a54e-9e91282b7133" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableCurrent_b58acb0a-101b-43f8-b2a8-beb96d1792ed" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccountsPayableCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_820b97dc-6442-4dd1-bb2a-ffe6447ec4e8" xlink:to="loc_us-gaap_AccountsPayableCurrent_b58acb0a-101b-43f8-b2a8-beb96d1792ed" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerAssetNetCurrent_54d3f211-8ed2-458f-9014-a35d5d01a760" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ContractWithCustomerAssetNetCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_820b97dc-6442-4dd1-bb2a-ffe6447ec4e8" xlink:to="loc_us-gaap_ContractWithCustomerAssetNetCurrent_54d3f211-8ed2-458f-9014-a35d5d01a760" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_NumberOfBoardSeats_e99cd9c2-520a-4d64-a6ab-75443366de3f" xlink:href="drs-20251231.xsd#drs_NumberOfBoardSeats"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_820b97dc-6442-4dd1-bb2a-ffe6447ec4e8" xlink:to="loc_drs_NumberOfBoardSeats_e99cd9c2-520a-4d64-a6ab-75443366de3f" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.leonardodrs.com/role/SegmentInformationRevenuesExpensesandEBITAbySegmentandReconciliationtoNetEarningsDetails" xlink:type="simple" xlink:href="drs-20251231.xsd#SegmentInformationRevenuesExpensesandEBITAbySegmentandReconciliationtoNetEarningsDetails"/>
  <link:definitionLink xlink:role="http://www.leonardodrs.com/role/SegmentInformationRevenuesExpensesandEBITAbySegmentandReconciliationtoNetEarningsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_ad1c9c6b-8434-49ea-babe-7932d434992b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_51d00e2b-7c28-466e-91db-fddb0675fed1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_ad1c9c6b-8434-49ea-babe-7932d434992b" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_51d00e2b-7c28-466e-91db-fddb0675fed1" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_a7740575-4f32-4218-b2cc-c82e62123d66" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_51d00e2b-7c28-466e-91db-fddb0675fed1" xlink:to="loc_srt_ConsolidationItemsAxis_a7740575-4f32-4218-b2cc-c82e62123d66" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_a7740575-4f32-4218-b2cc-c82e62123d66_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_a7740575-4f32-4218-b2cc-c82e62123d66" xlink:to="loc_srt_ConsolidationItemsDomain_a7740575-4f32-4218-b2cc-c82e62123d66_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_d82f0324-2480-4ef2-a334-8783baad95d7" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_a7740575-4f32-4218-b2cc-c82e62123d66" xlink:to="loc_srt_ConsolidationItemsDomain_d82f0324-2480-4ef2-a334-8783baad95d7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_42bc4273-4219-4cd3-8aa1-965367f732c2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_d82f0324-2480-4ef2-a334-8783baad95d7" xlink:to="loc_us-gaap_OperatingSegmentsMember_42bc4273-4219-4cd3-8aa1-965367f732c2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_CorporateAndEliminationsMember_f3357be6-d57b-4285-8181-506190471ab7" xlink:href="drs-20251231.xsd#drs_CorporateAndEliminationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_d82f0324-2480-4ef2-a334-8783baad95d7" xlink:to="loc_drs_CorporateAndEliminationsMember_f3357be6-d57b-4285-8181-506190471ab7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_be2af531-2685-4830-8e0c-d7ea1a522a82" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_51d00e2b-7c28-466e-91db-fddb0675fed1" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_be2af531-2685-4830-8e0c-d7ea1a522a82" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_be2af531-2685-4830-8e0c-d7ea1a522a82_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_be2af531-2685-4830-8e0c-d7ea1a522a82" xlink:to="loc_us-gaap_SegmentDomain_be2af531-2685-4830-8e0c-d7ea1a522a82_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_e45df489-0324-42f4-8e3b-d6c540053da6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_be2af531-2685-4830-8e0c-d7ea1a522a82" xlink:to="loc_us-gaap_SegmentDomain_e45df489-0324-42f4-8e3b-d6c540053da6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_AdvancedSensingAndComputingSegmentMember_84499f4d-6cff-4d32-9973-20fbcab88789" xlink:href="drs-20251231.xsd#drs_AdvancedSensingAndComputingSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_e45df489-0324-42f4-8e3b-d6c540053da6" xlink:to="loc_drs_AdvancedSensingAndComputingSegmentMember_84499f4d-6cff-4d32-9973-20fbcab88789" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_IntegratedMissionSystemsSegmentMember_783d7dc1-daa0-4b29-b847-14647a15d28a" xlink:href="drs-20251231.xsd#drs_IntegratedMissionSystemsSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_e45df489-0324-42f4-8e3b-d6c540053da6" xlink:to="loc_drs_IntegratedMissionSystemsSegmentMember_783d7dc1-daa0-4b29-b847-14647a15d28a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_0d7d3f3a-b6a6-4fb7-b8a5-734e2a05c2ff" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_ad1c9c6b-8434-49ea-babe-7932d434992b" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_0d7d3f3a-b6a6-4fb7-b8a5-734e2a05c2ff" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfRevenue_00e68d90-a785-48ac-b4aa-7f8053ea6c4c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CostOfRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_ad1c9c6b-8434-49ea-babe-7932d434992b" xlink:to="loc_us-gaap_CostOfRevenue_00e68d90-a785-48ac-b4aa-7f8053ea6c4c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherGeneralAndAdministrativeExpense_83df5e22-9677-46c2-9259-1f41f86015ba" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherGeneralAndAdministrativeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_ad1c9c6b-8434-49ea-babe-7932d434992b" xlink:to="loc_us-gaap_OtherGeneralAndAdministrativeExpense_83df5e22-9677-46c2-9259-1f41f86015ba" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpense_b7c1b24e-c7ca-426b-9db0-c63362dfca82" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ResearchAndDevelopmentExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_ad1c9c6b-8434-49ea-babe-7932d434992b" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpense_b7c1b24e-c7ca-426b-9db0-c63362dfca82" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_01d2995a-79bd-4856-a251-6712d7f7b667" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AmortizationOfIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_ad1c9c6b-8434-49ea-babe-7932d434992b" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_01d2995a-79bd-4856-a251-6712d7f7b667" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingOtherItemAmount_332ab960-df12-45b1-aefc-fd9c0e21cb4b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentReportingOtherItemAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_ad1c9c6b-8434-49ea-babe-7932d434992b" xlink:to="loc_us-gaap_SegmentReportingOtherItemAmount_332ab960-df12-45b1-aefc-fd9c0e21cb4b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_f7832a6c-dba2-4e40-bfa9-159359255b63" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_ad1c9c6b-8434-49ea-babe-7932d434992b" xlink:to="loc_us-gaap_OperatingIncomeLoss_f7832a6c-dba2-4e40-bfa9-159359255b63" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestIncomeExpenseNonoperatingNet_ae7a86d6-6a38-4583-949a-71be3e0da2ee" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestIncomeExpenseNonoperatingNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_ad1c9c6b-8434-49ea-babe-7932d434992b" xlink:to="loc_us-gaap_InterestIncomeExpenseNonoperatingNet_ae7a86d6-6a38-4583-949a-71be3e0da2ee" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpense_9b3de097-409c-41c9-abca-23c722b479f3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherNonoperatingIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_ad1c9c6b-8434-49ea-babe-7932d434992b" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpense_9b3de097-409c-41c9-abca-23c722b479f3" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_9b38a72f-ced1-4bbf-b67c-19267eada772" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_ad1c9c6b-8434-49ea-babe-7932d434992b" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_9b38a72f-ced1-4bbf-b67c-19267eada772" xlink:type="arc" order="9"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.leonardodrs.com/role/SegmentInformationRevenuesandIntersegmentRevenuesDetails" xlink:type="simple" xlink:href="drs-20251231.xsd#SegmentInformationRevenuesandIntersegmentRevenuesDetails"/>
  <link:definitionLink xlink:role="http://www.leonardodrs.com/role/SegmentInformationRevenuesandIntersegmentRevenuesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_39fbd791-edc2-41ae-9f3c-576fb0dcef8f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_a75fa27e-2a78-460a-be61-50d6d42977be" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_39fbd791-edc2-41ae-9f3c-576fb0dcef8f" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_a75fa27e-2a78-460a-be61-50d6d42977be" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_8a3ac92f-34fb-4867-85b5-93627c2a5464" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_a75fa27e-2a78-460a-be61-50d6d42977be" xlink:to="loc_srt_ConsolidationItemsAxis_8a3ac92f-34fb-4867-85b5-93627c2a5464" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_8a3ac92f-34fb-4867-85b5-93627c2a5464_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_8a3ac92f-34fb-4867-85b5-93627c2a5464" xlink:to="loc_srt_ConsolidationItemsDomain_8a3ac92f-34fb-4867-85b5-93627c2a5464_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_2dcb3b57-4fee-451d-afba-66d591aabccd" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_8a3ac92f-34fb-4867-85b5-93627c2a5464" xlink:to="loc_srt_ConsolidationItemsDomain_2dcb3b57-4fee-451d-afba-66d591aabccd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntersegmentEliminationMember_ee4bb0fa-9598-4aa9-83fe-489515a48d5a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IntersegmentEliminationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_2dcb3b57-4fee-451d-afba-66d591aabccd" xlink:to="loc_us-gaap_IntersegmentEliminationMember_ee4bb0fa-9598-4aa9-83fe-489515a48d5a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_e3909120-48e1-40cf-9b7a-9412317a8e55" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_a75fa27e-2a78-460a-be61-50d6d42977be" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_e3909120-48e1-40cf-9b7a-9412317a8e55" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_e3909120-48e1-40cf-9b7a-9412317a8e55_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_e3909120-48e1-40cf-9b7a-9412317a8e55" xlink:to="loc_us-gaap_SegmentDomain_e3909120-48e1-40cf-9b7a-9412317a8e55_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_6577e796-22cc-456d-9195-43659ffb9ec9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_e3909120-48e1-40cf-9b7a-9412317a8e55" xlink:to="loc_us-gaap_SegmentDomain_6577e796-22cc-456d-9195-43659ffb9ec9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_AdvancedSensingAndComputingSegmentMember_042ae770-7139-4e74-9e19-8e37d8eb6600" xlink:href="drs-20251231.xsd#drs_AdvancedSensingAndComputingSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_6577e796-22cc-456d-9195-43659ffb9ec9" xlink:to="loc_drs_AdvancedSensingAndComputingSegmentMember_042ae770-7139-4e74-9e19-8e37d8eb6600" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_IntegratedMissionSystemsSegmentMember_8ec7d290-6dbe-4aee-947a-d5af1394a425" xlink:href="drs-20251231.xsd#drs_IntegratedMissionSystemsSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_6577e796-22cc-456d-9195-43659ffb9ec9" xlink:to="loc_drs_IntegratedMissionSystemsSegmentMember_8ec7d290-6dbe-4aee-947a-d5af1394a425" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_6ec0dd6e-9958-4e79-8e71-908c75bcbb79" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_39fbd791-edc2-41ae-9f3c-576fb0dcef8f" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_6ec0dd6e-9958-4e79-8e71-908c75bcbb79" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.leonardodrs.com/role/SegmentInformationDepreciationbySegmentDetails" xlink:type="simple" xlink:href="drs-20251231.xsd#SegmentInformationDepreciationbySegmentDetails"/>
  <link:definitionLink xlink:role="http://www.leonardodrs.com/role/SegmentInformationDepreciationbySegmentDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_4c147582-c862-4642-9c77-17d4efc338a1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_46ca36b5-1413-47aa-9855-58880ebbdfe8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_4c147582-c862-4642-9c77-17d4efc338a1" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_46ca36b5-1413-47aa-9855-58880ebbdfe8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_644aa6e3-2bec-4cd1-a49f-7b7e57c45d2c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_46ca36b5-1413-47aa-9855-58880ebbdfe8" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_644aa6e3-2bec-4cd1-a49f-7b7e57c45d2c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_644aa6e3-2bec-4cd1-a49f-7b7e57c45d2c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_644aa6e3-2bec-4cd1-a49f-7b7e57c45d2c" xlink:to="loc_us-gaap_SegmentDomain_644aa6e3-2bec-4cd1-a49f-7b7e57c45d2c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_48f2bad1-c097-4e6b-bf50-181eec3e528f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_644aa6e3-2bec-4cd1-a49f-7b7e57c45d2c" xlink:to="loc_us-gaap_SegmentDomain_48f2bad1-c097-4e6b-bf50-181eec3e528f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_AdvancedSensingAndComputingSegmentMember_44f0b137-1ea2-49cd-a9da-f95135f04b1d" xlink:href="drs-20251231.xsd#drs_AdvancedSensingAndComputingSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_48f2bad1-c097-4e6b-bf50-181eec3e528f" xlink:to="loc_drs_AdvancedSensingAndComputingSegmentMember_44f0b137-1ea2-49cd-a9da-f95135f04b1d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_IntegratedMissionSystemsSegmentMember_65e49450-6ad7-4318-9911-006fb3bb0fce" xlink:href="drs-20251231.xsd#drs_IntegratedMissionSystemsSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_48f2bad1-c097-4e6b-bf50-181eec3e528f" xlink:to="loc_drs_IntegratedMissionSystemsSegmentMember_65e49450-6ad7-4318-9911-006fb3bb0fce" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Depreciation_737a46ae-0af6-447f-8778-404435d11cf5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Depreciation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_4c147582-c862-4642-9c77-17d4efc338a1" xlink:to="loc_us-gaap_Depreciation_737a46ae-0af6-447f-8778-404435d11cf5" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.leonardodrs.com/role/SegmentInformationTotalAssetsbySegmentDetails" xlink:type="simple" xlink:href="drs-20251231.xsd#SegmentInformationTotalAssetsbySegmentDetails"/>
  <link:definitionLink xlink:role="http://www.leonardodrs.com/role/SegmentInformationTotalAssetsbySegmentDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_579a49e8-adee-4b77-8e6a-b3595cf0b7e6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_faf58139-f9af-435c-8671-25967406c442" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_579a49e8-adee-4b77-8e6a-b3595cf0b7e6" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_faf58139-f9af-435c-8671-25967406c442" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_7026f751-7364-4788-864b-50e11d1c2bf6" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_faf58139-f9af-435c-8671-25967406c442" xlink:to="loc_srt_ConsolidationItemsAxis_7026f751-7364-4788-864b-50e11d1c2bf6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_7026f751-7364-4788-864b-50e11d1c2bf6_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_7026f751-7364-4788-864b-50e11d1c2bf6" xlink:to="loc_srt_ConsolidationItemsDomain_7026f751-7364-4788-864b-50e11d1c2bf6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_7d573e25-2f2b-4f9d-a912-076707f22f1a" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_7026f751-7364-4788-864b-50e11d1c2bf6" xlink:to="loc_srt_ConsolidationItemsDomain_7d573e25-2f2b-4f9d-a912-076707f22f1a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_fee3481b-1cdf-49bd-b478-cd1383d12479" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_7d573e25-2f2b-4f9d-a912-076707f22f1a" xlink:to="loc_us-gaap_OperatingSegmentsMember_fee3481b-1cdf-49bd-b478-cd1383d12479" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_CorporateAndEliminationsMember_e1dc4935-afa1-4ba1-a102-9522147b6b58" xlink:href="drs-20251231.xsd#drs_CorporateAndEliminationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_7d573e25-2f2b-4f9d-a912-076707f22f1a" xlink:to="loc_drs_CorporateAndEliminationsMember_e1dc4935-afa1-4ba1-a102-9522147b6b58" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_8adcf686-f099-4977-86e2-aceb6fdb0a51" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_faf58139-f9af-435c-8671-25967406c442" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_8adcf686-f099-4977-86e2-aceb6fdb0a51" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_8adcf686-f099-4977-86e2-aceb6fdb0a51_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_8adcf686-f099-4977-86e2-aceb6fdb0a51" xlink:to="loc_us-gaap_SegmentDomain_8adcf686-f099-4977-86e2-aceb6fdb0a51_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_b46b1419-8aa8-4295-9a06-3186736434bd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_8adcf686-f099-4977-86e2-aceb6fdb0a51" xlink:to="loc_us-gaap_SegmentDomain_b46b1419-8aa8-4295-9a06-3186736434bd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_AdvancedSensingAndComputingSegmentMember_bfc68af3-cfbc-473e-8736-37d7dc64d153" xlink:href="drs-20251231.xsd#drs_AdvancedSensingAndComputingSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_b46b1419-8aa8-4295-9a06-3186736434bd" xlink:to="loc_drs_AdvancedSensingAndComputingSegmentMember_bfc68af3-cfbc-473e-8736-37d7dc64d153" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_drs_IntegratedMissionSystemsSegmentMember_e9c19990-269f-420f-90cf-f7129c74edd3" xlink:href="drs-20251231.xsd#drs_IntegratedMissionSystemsSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_b46b1419-8aa8-4295-9a06-3186736434bd" xlink:to="loc_drs_IntegratedMissionSystemsSegmentMember_e9c19990-269f-420f-90cf-f7129c74edd3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_6c5af556-2566-41fb-905d-2fae167060e8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Assets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_579a49e8-adee-4b77-8e6a-b3595cf0b7e6" xlink:to="loc_us-gaap_Assets_6c5af556-2566-41fb-905d-2fae167060e8" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://fasb.org/us-gaap/role/eedm/ExtensibleEnumerationLists" xlink:type="simple" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-roles-2025.xsd#eedm"/>
  <link:definitionLink xlink:role="http://fasb.org/us-gaap/role/eedm/ExtensibleEnumerationLists" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssetsNoncurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherAssetsNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract" xlink:to="loc_us-gaap_OtherAssetsNoncurrent" xlink:type="arc" order="101"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization" xlink:type="arc" order="102"/>
  </link:definitionLink>
</link:linkbase>
