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

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:019f660f-6949-707e-9b78-76c0778156af,g:230243e7-22c0-42a7-8867-7201766ae9d9-->
<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.xtiaircraft.com/role/CONDENSEDCONSOLIDATEDBALANCESHEETS" xlink:type="simple" xlink:href="xtia-20260630.xsd#CONDENSEDCONSOLIDATEDBALANCESHEETS"/>
  <link:definitionLink xlink:role="http://www.xtiaircraft.com/role/CONDENSEDCONSOLIDATEDBALANCESHEETS" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019f660f-69f5-75c1-a6c5-a2029cb3e101" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_019f660f-69f5-7c93-920e-62f1840b5f8e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019f660f-69f5-75c1-a6c5-a2029cb3e101" xlink:to="loc_us-gaap_StatementTable_019f660f-69f5-7c93-920e-62f1840b5f8e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_019f660f-69f5-76b5-8cce-293f7bdf420e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019f660f-69f5-7c93-920e-62f1840b5f8e" xlink:to="loc_us-gaap_StatementClassOfStockAxis_019f660f-69f5-76b5-8cce-293f7bdf420e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_019f660f-69f5-76b5-8cce-293f7bdf420e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_019f660f-69f5-76b5-8cce-293f7bdf420e" xlink:to="loc_us-gaap_ClassOfStockDomain_019f660f-69f5-76b5-8cce-293f7bdf420e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_019f660f-69f5-7439-af6a-802be7392923" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_019f660f-69f5-76b5-8cce-293f7bdf420e" xlink:to="loc_us-gaap_ClassOfStockDomain_019f660f-69f5-7439-af6a-802be7392923" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockMember_019fd8aa-6a31-7542-81ef-9ae834df3558" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019f660f-69f5-7439-af6a-802be7392923" xlink:to="loc_us-gaap_PreferredStockMember_019fd8aa-6a31-7542-81ef-9ae834df3558" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_Series4ConvertiblePreferredStockMember_019f660f-69f5-7a16-ae70-776d509cf863" xlink:href="xtia-20260630.xsd#xtia_Series4ConvertiblePreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PreferredStockMember_019fd8aa-6a31-7542-81ef-9ae834df3558" xlink:to="loc_xtia_Series4ConvertiblePreferredStockMember_019f660f-69f5-7a16-ae70-776d509cf863" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_Series5ConvertiblePreferredStockMember_019f660f-69f5-7c7e-a513-ca7fa9c63ade" xlink:href="xtia-20260630.xsd#xtia_Series5ConvertiblePreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PreferredStockMember_019fd8aa-6a31-7542-81ef-9ae834df3558" xlink:to="loc_xtia_Series5ConvertiblePreferredStockMember_019f660f-69f5-7c7e-a513-ca7fa9c63ade" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_Series9ConvertiblePreferredStockMember_01a01f79-1cb6-747a-94e3-fded674655e4" xlink:href="xtia-20260630.xsd#xtia_Series9ConvertiblePreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PreferredStockMember_019fd8aa-6a31-7542-81ef-9ae834df3558" xlink:to="loc_xtia_Series9ConvertiblePreferredStockMember_01a01f79-1cb6-747a-94e3-fded674655e4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_Series10ConvertiblePreferredStockMember_019f660f-69f5-7995-9c57-256d86dfa081" xlink:href="xtia-20260630.xsd#xtia_Series10ConvertiblePreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PreferredStockMember_019fd8aa-6a31-7542-81ef-9ae834df3558" xlink:to="loc_xtia_Series10ConvertiblePreferredStockMember_019f660f-69f5-7995-9c57-256d86dfa081" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019f660f-69f5-71ca-b9f0-7490a9207f51" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019f660f-69f5-7c93-920e-62f1840b5f8e" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019f660f-69f5-71ca-b9f0-7490a9207f51" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_019f660f-69f5-71ca-b9f0-7490a9207f51_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019f660f-69f5-71ca-b9f0-7490a9207f51" xlink:to="loc_us-gaap_RelatedPartyDomain_019f660f-69f5-71ca-b9f0-7490a9207f51_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_019f660f-69f5-7ac4-804e-32ee6f8886e3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019f660f-69f5-71ca-b9f0-7490a9207f51" xlink:to="loc_us-gaap_RelatedPartyDomain_019f660f-69f5-7ac4-804e-32ee6f8886e3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyMember_019f660f-69f5-76b7-b083-bc616715b6e9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_019f660f-69f5-7ac4-804e-32ee6f8886e3" xlink:to="loc_us-gaap_RelatedPartyMember_019f660f-69f5-76b7-b083-bc616715b6e9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsAbstract_019f8506-3978-71ee-9577-1bad3da8e296" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019f660f-69f5-75c1-a6c5-a2029cb3e101" xlink:to="loc_us-gaap_AssetsAbstract_019f8506-3978-71ee-9577-1bad3da8e296" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrentAbstract_019f660f-69f5-7e70-a280-f2220e96f2b6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetsCurrentAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019f8506-3978-71ee-9577-1bad3da8e296" xlink:to="loc_us-gaap_AssetsCurrentAbstract_019f660f-69f5-7e70-a280-f2220e96f2b6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_019f660f-69f5-7b30-908e-0c30c6d7d189" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_019f660f-69f5-7e70-a280-f2220e96f2b6" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_019f660f-69f5-7b30-908e-0c30c6d7d189" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableNetCurrent_019f660f-69f5-7364-88ce-e65b561be412" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccountsReceivableNetCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_019f660f-69f5-7e70-a280-f2220e96f2b6" xlink:to="loc_us-gaap_AccountsReceivableNetCurrent_019f660f-69f5-7364-88ce-e65b561be412" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryNet_019f660f-69f5-7073-92a4-7ad923c02bee" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InventoryNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_019f660f-69f5-7e70-a280-f2220e96f2b6" xlink:to="loc_us-gaap_InventoryNet_019f660f-69f5-7073-92a4-7ad923c02bee" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_019f660f-69f5-7f76-86be-06f29df6b5a2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PrepaidExpenseAndOtherAssetsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_019f660f-69f5-7e70-a280-f2220e96f2b6" xlink:to="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_019f660f-69f5-7f76-86be-06f29df6b5a2" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent_019f660f-69f5-7193-ab47-6e83fd595748" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_019f660f-69f5-7e70-a280-f2220e96f2b6" xlink:to="loc_us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent_019f660f-69f5-7193-ab47-6e83fd595748" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsCurrent_019f660f-69f5-7c86-89d0-6e30cb6864a2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsCurrentAbstract_019f660f-69f5-7e70-a280-f2220e96f2b6" xlink:to="loc_us-gaap_AssetsCurrent_019f660f-69f5-7c86-89d0-6e30cb6864a2" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_019f660f-69f5-7355-ab05-ab4ee2ecedc4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019f8506-3978-71ee-9577-1bad3da8e296" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_019f660f-69f5-7355-ab05-ab4ee2ecedc4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseRightOfUseAsset_019f660f-69f5-7a26-a656-51fde9728594" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingLeaseRightOfUseAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019f8506-3978-71ee-9577-1bad3da8e296" xlink:to="loc_us-gaap_OperatingLeaseRightOfUseAsset_019f660f-69f5-7a26-a656-51fde9728594" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_019f660f-69f5-7d1a-9caa-bd85a3a2cb0d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019f8506-3978-71ee-9577-1bad3da8e296" xlink:to="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_019f660f-69f5-7d1a-9caa-bd85a3a2cb0d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_019f660f-69f5-7242-89fb-9fd98840b129" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019f8506-3978-71ee-9577-1bad3da8e296" xlink:to="loc_us-gaap_Goodwill_019f660f-69f5-7242-89fb-9fd98840b129" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NotesAndLoansReceivableNetNoncurrent_019f660f-69f5-7590-ba97-6fe88a0172e3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NotesAndLoansReceivableNetNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019f8506-3978-71ee-9577-1bad3da8e296" xlink:to="loc_us-gaap_NotesAndLoansReceivableNetNoncurrent_019f660f-69f5-7590-ba97-6fe88a0172e3" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssetsNoncurrent_019f660f-69f5-7172-a418-0ed9843082a0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherAssetsNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019f8506-3978-71ee-9577-1bad3da8e296" xlink:to="loc_us-gaap_OtherAssetsNoncurrent_019f660f-69f5-7172-a418-0ed9843082a0" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationAssetsNoncurrent_019f660f-69f5-73f8-838a-b4b520999b91" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationAssetsNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019f8506-3978-71ee-9577-1bad3da8e296" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationAssetsNoncurrent_019f660f-69f5-73f8-838a-b4b520999b91" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_019f660f-69f5-70ab-9a00-f2b263182588" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Assets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract_019f8506-3978-71ee-9577-1bad3da8e296" xlink:to="loc_us-gaap_Assets_019f660f-69f5-70ab-9a00-f2b263182588" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019f8507-1538-79db-bb6a-03d2fd379517" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesAndStockholdersEquityAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019f660f-69f5-75c1-a6c5-a2029cb3e101" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019f8507-1538-79db-bb6a-03d2fd379517" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrentAbstract_019f660f-69f5-78ac-9552-eab47f614943" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesCurrentAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019f8507-1538-79db-bb6a-03d2fd379517" xlink:to="loc_us-gaap_LiabilitiesCurrentAbstract_019f660f-69f5-78ac-9552-eab47f614943" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableCurrent_019f660f-69f5-7ce9-bf83-2870e3c8a4a3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccountsPayableCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019f660f-69f5-78ac-9552-eab47f614943" xlink:to="loc_us-gaap_AccountsPayableCurrent_019f660f-69f5-7ce9-bf83-2870e3c8a4a3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableAndOtherAccruedLiabilitiesCurrent_019f660f-69f5-7ba7-9bd4-88c841a97e55" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccountsPayableAndOtherAccruedLiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019f660f-69f5-78ac-9552-eab47f614943" xlink:to="loc_us-gaap_AccountsPayableAndOtherAccruedLiabilitiesCurrent_019f660f-69f5-7ba7-9bd4-88c841a97e55" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepositLiabilityCurrent_019f660f-69f5-7da9-9c82-6aa9adb00ab5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DepositLiabilityCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019f660f-69f5-78ac-9552-eab47f614943" xlink:to="loc_us-gaap_DepositLiabilityCurrent_019f660f-69f5-7da9-9c82-6aa9adb00ab5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilitiesCurrent_019f660f-69f5-71cf-a00d-531b2cd35416" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019f660f-69f5-78ac-9552-eab47f614943" xlink:to="loc_us-gaap_DerivativeLiabilitiesCurrent_019f660f-69f5-71cf-a00d-531b2cd35416" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityCurrent_019f660f-69f5-78f3-97cd-20afbc355b2b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingLeaseLiabilityCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019f660f-69f5-78ac-9552-eab47f614943" xlink:to="loc_us-gaap_OperatingLeaseLiabilityCurrent_019f660f-69f5-78f3-97cd-20afbc355b2b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NotesPayableCurrent_01a000d4-fce3-77ac-9aa8-a9f03ee4e38b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NotesPayableCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019f660f-69f5-78ac-9552-eab47f614943" xlink:to="loc_us-gaap_NotesPayableCurrent_01a000d4-fce3-77ac-9aa8-a9f03ee4e38b" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_AcquisitionRelatedPromissoryNotePaybleCurrent_019f660f-69f5-7b2d-9635-c80a8f14ec1d" xlink:href="xtia-20260630.xsd#xtia_AcquisitionRelatedPromissoryNotePaybleCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019f660f-69f5-78ac-9552-eab47f614943" xlink:to="loc_xtia_AcquisitionRelatedPromissoryNotePaybleCurrent_019f660f-69f5-7b2d-9635-c80a8f14ec1d" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LinesOfCreditCurrent_01a000d6-c9ff-777d-92e0-10a6c80a8c80" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LinesOfCreditCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019f660f-69f5-78ac-9552-eab47f614943" xlink:to="loc_us-gaap_LinesOfCreditCurrent_01a000d6-c9ff-777d-92e0-10a6c80a8c80" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxesPayableCurrent_019f660f-69f5-7c43-8eee-4f8011450ce8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TaxesPayableCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019f660f-69f5-78ac-9552-eab47f614943" xlink:to="loc_us-gaap_TaxesPayableCurrent_019f660f-69f5-7c43-8eee-4f8011450ce8" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent_019f660f-69f5-75d3-8364-daba486d4785" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019f660f-69f5-78ac-9552-eab47f614943" xlink:to="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent_019f660f-69f5-75d3-8364-daba486d4785" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrent_019f660f-69f5-79d2-8150-33dc49e46166" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract_019f660f-69f5-78ac-9552-eab47f614943" xlink:to="loc_us-gaap_LiabilitiesCurrent_019f660f-69f5-79d2-8150-33dc49e46166" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermNotesPayable_019f660f-69f5-706f-857c-0d368a635d7b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermNotesPayable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019f8507-1538-79db-bb6a-03d2fd379517" xlink:to="loc_us-gaap_LongTermNotesPayable_019f660f-69f5-706f-857c-0d368a635d7b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_019f660f-69f5-7aab-8d8e-5b47179725f8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingLeaseLiabilityNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019f8507-1538-79db-bb6a-03d2fd379517" xlink:to="loc_us-gaap_OperatingLeaseLiabilityNoncurrent_019f660f-69f5-7aab-8d8e-5b47179725f8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationNoncurrent_019f660f-69f5-7dd3-b5e6-e9ae7dcda493" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019f8507-1538-79db-bb6a-03d2fd379517" xlink:to="loc_us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationNoncurrent_019f660f-69f5-7dd3-b5e6-e9ae7dcda493" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Liabilities_019f660f-69f5-7f31-b1bd-860641e0bff0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Liabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019f8507-1538-79db-bb6a-03d2fd379517" xlink:to="loc_us-gaap_Liabilities_019f660f-69f5-7f31-b1bd-860641e0bff0" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommitmentsAndContingencies_019f660f-69f5-7160-b0dd-11812b7e5e9e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommitmentsAndContingencies"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019f8507-1538-79db-bb6a-03d2fd379517" xlink:to="loc_us-gaap_CommitmentsAndContingencies_019f660f-69f5-7160-b0dd-11812b7e5e9e" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquityAbstract_019f660f-69f5-77d1-8150-05526b0fffff" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TemporaryEquityAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019f8507-1538-79db-bb6a-03d2fd379517" xlink:to="loc_us-gaap_TemporaryEquityAbstract_019f660f-69f5-77d1-8150-05526b0fffff" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TemporaryEquityCarryingAmountAttributableToParent_019f660f-69f5-7658-a763-b878a422abd5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TemporaryEquityCarryingAmountAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TemporaryEquityAbstract_019f660f-69f5-77d1-8150-05526b0fffff" xlink:to="loc_us-gaap_TemporaryEquityCarryingAmountAttributableToParent_019f660f-69f5-7658-a763-b878a422abd5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityAbstract_019f660f-69f5-7d6e-9306-a2aa2685c277" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquityAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019f8507-1538-79db-bb6a-03d2fd379517" xlink:to="loc_us-gaap_StockholdersEquityAbstract_019f660f-69f5-7d6e-9306-a2aa2685c277" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockValue_019f660f-69f5-7d6d-91a2-c468c5e79374" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_019f660f-69f5-7d6e-9306-a2aa2685c277" xlink:to="loc_us-gaap_PreferredStockValue_019f660f-69f5-7d6d-91a2-c468c5e79374" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockValue_019f660f-69f5-7c7b-9231-e3ea79a7158f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_019f660f-69f5-7d6e-9306-a2aa2685c277" xlink:to="loc_us-gaap_CommonStockValue_019f660f-69f5-7c7b-9231-e3ea79a7158f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapital_019f660f-69f5-77b1-a4e4-97e2fb81d7c7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdditionalPaidInCapital"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_019f660f-69f5-7d6e-9306-a2aa2685c277" xlink:to="loc_us-gaap_AdditionalPaidInCapital_019f660f-69f5-77b1-a4e4-97e2fb81d7c7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_019f660f-69f5-7081-9b8e-23fbad5e8391" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_019f660f-69f5-7d6e-9306-a2aa2685c277" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_019f660f-69f5-7081-9b8e-23fbad5e8391" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit_019f660f-69f5-7943-849f-f764d08cf775" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RetainedEarningsAccumulatedDeficit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_019f660f-69f5-7d6e-9306-a2aa2685c277" xlink:to="loc_us-gaap_RetainedEarningsAccumulatedDeficit_019f660f-69f5-7943-849f-f764d08cf775" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019f660f-69f5-7524-9243-a165ef1b153a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StockholdersEquityAbstract_019f660f-69f5-7d6e-9306-a2aa2685c277" xlink:to="loc_us-gaap_StockholdersEquity_019f660f-69f5-7524-9243-a165ef1b153a" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterest_019f660f-69f5-7cee-ab1f-8a9ab46394e0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MinorityInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019f8507-1538-79db-bb6a-03d2fd379517" xlink:to="loc_us-gaap_MinorityInterest_019f660f-69f5-7cee-ab1f-8a9ab46394e0" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019f660f-69f5-7074-967c-1aade09fa16c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019f8507-1538-79db-bb6a-03d2fd379517" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019f660f-69f5-7074-967c-1aade09fa16c" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquity_019f660f-69f5-7b17-acc8-be75fd8303f1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LiabilitiesAndStockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_019f8507-1538-79db-bb6a-03d2fd379517" xlink:to="loc_us-gaap_LiabilitiesAndStockholdersEquity_019f660f-69f5-7b17-acc8-be75fd8303f1" xlink:type="arc" order="11"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.xtiaircraft.com/role/CONDENSEDCONSOLIDATEDBALANCESHEETSParenthetical" xlink:type="simple" xlink:href="xtia-20260630.xsd#CONDENSEDCONSOLIDATEDBALANCESHEETSParenthetical"/>
  <link:definitionLink xlink:role="http://www.xtiaircraft.com/role/CONDENSEDCONSOLIDATEDBALANCESHEETSParenthetical" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019f660f-69f5-7512-926f-07c646a2b554" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_019f660f-69f5-7b79-8178-9914ce48a75d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019f660f-69f5-7512-926f-07c646a2b554" xlink:to="loc_us-gaap_StatementTable_019f660f-69f5-7b79-8178-9914ce48a75d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_019f660f-69f5-7ebc-8cae-cf23ef87ca8a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019f660f-69f5-7b79-8178-9914ce48a75d" xlink:to="loc_us-gaap_StatementClassOfStockAxis_019f660f-69f5-7ebc-8cae-cf23ef87ca8a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_019f660f-69f5-7ebc-8cae-cf23ef87ca8a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_019f660f-69f5-7ebc-8cae-cf23ef87ca8a" xlink:to="loc_us-gaap_ClassOfStockDomain_019f660f-69f5-7ebc-8cae-cf23ef87ca8a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_019f660f-69f5-7384-9fc7-0f1afc5a3062" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_019f660f-69f5-7ebc-8cae-cf23ef87ca8a" xlink:to="loc_us-gaap_ClassOfStockDomain_019f660f-69f5-7384-9fc7-0f1afc5a3062" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_Series4ConvertiblePreferredStockMember_019f660f-69f5-7090-bb53-07c7e96351e9" xlink:href="xtia-20260630.xsd#xtia_Series4ConvertiblePreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019f660f-69f5-7384-9fc7-0f1afc5a3062" xlink:to="loc_xtia_Series4ConvertiblePreferredStockMember_019f660f-69f5-7090-bb53-07c7e96351e9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_Series5ConvertiblePreferredStockMember_019f660f-69f5-7c4c-adf2-249f8d348e01" xlink:href="xtia-20260630.xsd#xtia_Series5ConvertiblePreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019f660f-69f5-7384-9fc7-0f1afc5a3062" xlink:to="loc_xtia_Series5ConvertiblePreferredStockMember_019f660f-69f5-7c4c-adf2-249f8d348e01" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_Series9ConvertiblePreferredStockMember_01a01f7b-539a-72b0-89ef-4cf6cdc113c0" xlink:href="xtia-20260630.xsd#xtia_Series9ConvertiblePreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019f660f-69f5-7384-9fc7-0f1afc5a3062" xlink:to="loc_xtia_Series9ConvertiblePreferredStockMember_01a01f7b-539a-72b0-89ef-4cf6cdc113c0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_Series10ConvertiblePreferredStockMember_019f660f-69f5-7130-ae50-1a3f9988c88a" xlink:href="xtia-20260630.xsd#xtia_Series10ConvertiblePreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019f660f-69f5-7384-9fc7-0f1afc5a3062" xlink:to="loc_xtia_Series10ConvertiblePreferredStockMember_019f660f-69f5-7130-ae50-1a3f9988c88a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NotesPayableCurrentRelatedPartyTypeExtensibleEnumeration_01a000d8-6c23-75bf-931b-cec5bb22c343" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NotesPayableCurrentRelatedPartyTypeExtensibleEnumeration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019f660f-69f5-7512-926f-07c646a2b554" xlink:to="loc_us-gaap_NotesPayableCurrentRelatedPartyTypeExtensibleEnumeration_01a000d8-6c23-75bf-931b-cec5bb22c343" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NotesPayableNoncurrentRelatedPartyTypeExtensibleEnumeration_01a000d9-587c-74b0-b1a1-5c1562a13828" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NotesPayableNoncurrentRelatedPartyTypeExtensibleEnumeration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019f660f-69f5-7512-926f-07c646a2b554" xlink:to="loc_us-gaap_NotesPayableNoncurrentRelatedPartyTypeExtensibleEnumeration_01a000d9-587c-74b0-b1a1-5c1562a13828" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockParOrStatedValuePerShare_019f660f-69f5-7cf7-92a9-0215bb09c6af" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockParOrStatedValuePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019f660f-69f5-7512-926f-07c646a2b554" xlink:to="loc_us-gaap_PreferredStockParOrStatedValuePerShare_019f660f-69f5-7cf7-92a9-0215bb09c6af" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesAuthorized_019f660f-69f5-7940-9038-822c1e3a0537" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019f660f-69f5-7512-926f-07c646a2b554" xlink:to="loc_us-gaap_PreferredStockSharesAuthorized_019f660f-69f5-7940-9038-822c1e3a0537" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesIssued_019f660f-69f5-7970-a257-e0a5447618e9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019f660f-69f5-7512-926f-07c646a2b554" xlink:to="loc_us-gaap_PreferredStockSharesIssued_019f660f-69f5-7970-a257-e0a5447618e9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesOutstanding_019f660f-69f5-749c-97ea-0ee8ff289a30" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019f660f-69f5-7512-926f-07c646a2b554" xlink:to="loc_us-gaap_PreferredStockSharesOutstanding_019f660f-69f5-749c-97ea-0ee8ff289a30" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockParOrStatedValuePerShare_019f660f-69f5-7563-8d10-b8e7f47dfce5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockParOrStatedValuePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019f660f-69f5-7512-926f-07c646a2b554" xlink:to="loc_us-gaap_CommonStockParOrStatedValuePerShare_019f660f-69f5-7563-8d10-b8e7f47dfce5" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesAuthorized_019f660f-69f5-711a-90c6-c8c72a0462ed" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019f660f-69f5-7512-926f-07c646a2b554" xlink:to="loc_us-gaap_CommonStockSharesAuthorized_019f660f-69f5-711a-90c6-c8c72a0462ed" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesIssued_019f660f-69f5-7800-95e4-fd6e1402b3d3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019f660f-69f5-7512-926f-07c646a2b554" xlink:to="loc_us-gaap_CommonStockSharesIssued_019f660f-69f5-7800-95e4-fd6e1402b3d3" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_019f660f-69f5-7ce9-9315-ad590bdc9b36" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019f660f-69f5-7512-926f-07c646a2b554" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_019f660f-69f5-7ce9-9315-ad590bdc9b36" xlink:type="arc" order="9"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.xtiaircraft.com/role/CONDENSEDCONSOLIDATEDSTATEMENTOFCHANGESINSTOCKHOLDERSEQUITYDEFICIT" xlink:type="simple" xlink:href="xtia-20260630.xsd#CONDENSEDCONSOLIDATEDSTATEMENTOFCHANGESINSTOCKHOLDERSEQUITYDEFICIT"/>
  <link:definitionLink xlink:role="http://www.xtiaircraft.com/role/CONDENSEDCONSOLIDATEDSTATEMENTOFCHANGESINSTOCKHOLDERSEQUITYDEFICIT" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019f660f-69f5-74ca-8ab9-8977cb5a1a4e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_019f660f-69f5-799e-916a-8730274b2703" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019f660f-69f5-74ca-8ab9-8977cb5a1a4e" xlink:to="loc_us-gaap_StatementTable_019f660f-69f5-799e-916a-8730274b2703" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_019f660f-69f5-7ea2-9757-84b2508b3f4a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019f660f-69f5-799e-916a-8730274b2703" xlink:to="loc_us-gaap_StatementClassOfStockAxis_019f660f-69f5-7ea2-9757-84b2508b3f4a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_019f660f-69f5-7ea2-9757-84b2508b3f4a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_019f660f-69f5-7ea2-9757-84b2508b3f4a" xlink:to="loc_us-gaap_ClassOfStockDomain_019f660f-69f5-7ea2-9757-84b2508b3f4a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_019f660f-69f5-72bf-83dc-3a579c45e5f3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_019f660f-69f5-7ea2-9757-84b2508b3f4a" xlink:to="loc_us-gaap_ClassOfStockDomain_019f660f-69f5-72bf-83dc-3a579c45e5f3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_Series4ConvertiblePreferredStockMember_01a01f7c-efb0-777d-9124-ac3d67174f18" xlink:href="xtia-20260630.xsd#xtia_Series4ConvertiblePreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019f660f-69f5-72bf-83dc-3a579c45e5f3" xlink:to="loc_xtia_Series4ConvertiblePreferredStockMember_01a01f7c-efb0-777d-9124-ac3d67174f18" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_Series5ConvertiblePreferredStockMember_01a01f7d-2eb9-737a-aa4c-1d2dc1d0e627" xlink:href="xtia-20260630.xsd#xtia_Series5ConvertiblePreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019f660f-69f5-72bf-83dc-3a579c45e5f3" xlink:to="loc_xtia_Series5ConvertiblePreferredStockMember_01a01f7d-2eb9-737a-aa4c-1d2dc1d0e627" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_Series9ConvertiblePreferredStockMember_01a01f7d-5da7-78b1-9206-6db002b68fbe" xlink:href="xtia-20260630.xsd#xtia_Series9ConvertiblePreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019f660f-69f5-72bf-83dc-3a579c45e5f3" xlink:to="loc_xtia_Series9ConvertiblePreferredStockMember_01a01f7d-5da7-78b1-9206-6db002b68fbe" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_Series10ConvertiblePreferredStockMember_019f660f-69f5-765f-a4af-b54b55a702e6" xlink:href="xtia-20260630.xsd#xtia_Series10ConvertiblePreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019f660f-69f5-72bf-83dc-3a579c45e5f3" xlink:to="loc_xtia_Series10ConvertiblePreferredStockMember_019f660f-69f5-765f-a4af-b54b55a702e6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_019f660f-69f5-781b-a175-e03d394be818" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019f660f-69f5-799e-916a-8730274b2703" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_019f660f-69f5-781b-a175-e03d394be818" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019f660f-69f5-781b-a175-e03d394be818_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019f660f-69f5-781b-a175-e03d394be818" xlink:to="loc_us-gaap_EquityComponentDomain_019f660f-69f5-781b-a175-e03d394be818_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019f660f-69f5-7727-984a-7a8b1caa3c36" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019f660f-69f5-781b-a175-e03d394be818" xlink:to="loc_us-gaap_EquityComponentDomain_019f660f-69f5-7727-984a-7a8b1caa3c36" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ParentMember_019f660f-69f5-7d67-bb70-5ed57c2ac0ff" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ParentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019f660f-69f5-7727-984a-7a8b1caa3c36" xlink:to="loc_us-gaap_ParentMember_019f660f-69f5-7d67-bb70-5ed57c2ac0ff" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockMember_019f660f-69f5-7f3c-8d75-09745ddcaff4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ParentMember_019f660f-69f5-7d67-bb70-5ed57c2ac0ff" xlink:to="loc_us-gaap_PreferredStockMember_019f660f-69f5-7f3c-8d75-09745ddcaff4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_019f660f-69f5-74ff-b2cb-414599ab11e3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ParentMember_019f660f-69f5-7d67-bb70-5ed57c2ac0ff" xlink:to="loc_us-gaap_CommonStockMember_019f660f-69f5-74ff-b2cb-414599ab11e3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_019f660f-69f5-7e01-95e0-489992e67702" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ParentMember_019f660f-69f5-7d67-bb70-5ed57c2ac0ff" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_019f660f-69f5-7e01-95e0-489992e67702" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019f660f-69f5-7bd3-967b-1984d9c9684c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ParentMember_019f660f-69f5-7d67-bb70-5ed57c2ac0ff" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019f660f-69f5-7bd3-967b-1984d9c9684c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_019f660f-69f5-7179-ac9e-db1552c1bf59" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ParentMember_019f660f-69f5-7d67-bb70-5ed57c2ac0ff" xlink:to="loc_us-gaap_RetainedEarningsMember_019f660f-69f5-7179-ac9e-db1552c1bf59" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncontrollingInterestMember_019f660f-69f5-7e98-bfd2-c396b91672c7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NoncontrollingInterestMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019f660f-69f5-7727-984a-7a8b1caa3c36" xlink:to="loc_us-gaap_NoncontrollingInterestMember_019f660f-69f5-7e98-bfd2-c396b91672c7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesOutstanding_019f660f-69f5-7152-a2ab-cf2d1ed20521" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019f660f-69f5-74ca-8ab9-8977cb5a1a4e" xlink:to="loc_us-gaap_SharesOutstanding_019f660f-69f5-7152-a2ab-cf2d1ed20521" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019f660f-69f5-7e6e-b065-4dcc9b76423b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019f660f-69f5-74ca-8ab9-8977cb5a1a4e" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019f660f-69f5-7e6e-b065-4dcc9b76423b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_StockIssuedDuringPeriodCommonShareIssuedInExchangeOfPreferredStock_01a15581-b347-7c23-b752-08932eaa2b0e" xlink:href="xtia-20260630.xsd#xtia_StockIssuedDuringPeriodCommonShareIssuedInExchangeOfPreferredStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019f660f-69f5-74ca-8ab9-8977cb5a1a4e" xlink:to="loc_xtia_StockIssuedDuringPeriodCommonShareIssuedInExchangeOfPreferredStock_01a15581-b347-7c23-b752-08932eaa2b0e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_StockIssuedDuringPeriodCommonSharesIssuedInExchangeOfPreferredStock_01a15581-b347-76a0-89db-4b0a784ab53b" xlink:href="xtia-20260630.xsd#xtia_StockIssuedDuringPeriodCommonSharesIssuedInExchangeOfPreferredStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019f660f-69f5-74ca-8ab9-8977cb5a1a4e" xlink:to="loc_xtia_StockIssuedDuringPeriodCommonSharesIssuedInExchangeOfPreferredStock_01a15581-b347-76a0-89db-4b0a784ab53b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_01a15582-4be1-793f-a566-bbd828fcda5d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019f660f-69f5-74ca-8ab9-8977cb5a1a4e" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_01a15582-4be1-793f-a566-bbd828fcda5d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationStockOptionsRequisiteServicePeriodRecognition_01a15581-b347-7692-80c5-860e4af5b011" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationStockOptionsRequisiteServicePeriodRecognition"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019f660f-69f5-74ca-8ab9-8977cb5a1a4e" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationStockOptionsRequisiteServicePeriodRecognition_01a15581-b347-7692-80c5-860e4af5b011" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_StockIssuedDuringPeriodSharesCommonShareIssuedForExerciseOfLiabilityClassifiedWarrants_01a15581-b347-7190-a58b-a8783a6c805f" xlink:href="xtia-20260630.xsd#xtia_StockIssuedDuringPeriodSharesCommonShareIssuedForExerciseOfLiabilityClassifiedWarrants"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019f660f-69f5-74ca-8ab9-8977cb5a1a4e" xlink:to="loc_xtia_StockIssuedDuringPeriodSharesCommonShareIssuedForExerciseOfLiabilityClassifiedWarrants_01a15581-b347-7190-a58b-a8783a6c805f" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_StockIssuedDuringPeriodValueCommonSharesIssuedForExerciseOfLiabilityClassifiedWarrants_01a15581-b347-751a-947c-231241e73935" xlink:href="xtia-20260630.xsd#xtia_StockIssuedDuringPeriodValueCommonSharesIssuedForExerciseOfLiabilityClassifiedWarrants"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019f660f-69f5-74ca-8ab9-8977cb5a1a4e" xlink:to="loc_xtia_StockIssuedDuringPeriodValueCommonSharesIssuedForExerciseOfLiabilityClassifiedWarrants_01a15581-b347-751a-947c-231241e73935" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalIncreaseInCarryingAmountOfRedeemablePreferredStock_01a15581-b347-71b9-a841-488c84725c2b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalIncreaseInCarryingAmountOfRedeemablePreferredStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019f660f-69f5-74ca-8ab9-8977cb5a1a4e" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalIncreaseInCarryingAmountOfRedeemablePreferredStock_01a15581-b347-71b9-a841-488c84725c2b" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_AOCIDecreaseFromBusinessDisposition_01a15581-b347-77c8-acc3-ad663d9ca6bd" xlink:href="xtia-20260630.xsd#xtia_AOCIDecreaseFromBusinessDisposition"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019f660f-69f5-74ca-8ab9-8977cb5a1a4e" xlink:to="loc_xtia_AOCIDecreaseFromBusinessDisposition_01a15581-b347-77c8-acc3-ad663d9ca6bd" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_01a15581-b347-7998-b779-282ce50afb7c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019f660f-69f5-74ca-8ab9-8977cb5a1a4e" xlink:to="loc_us-gaap_NetIncomeLoss_01a15581-b347-7998-b779-282ce50afb7c" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest_01a15581-b347-76cc-bc78-522338cd4283" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLossAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019f660f-69f5-74ca-8ab9-8977cb5a1a4e" xlink:to="loc_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest_01a15581-b347-76cc-bc78-522338cd4283" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_01a15582-0c80-7474-98be-fa4cc77c209e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019f660f-69f5-74ca-8ab9-8977cb5a1a4e" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_01a15582-0c80-7474-98be-fa4cc77c209e" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_StockIssuedDuringPeriodCommonSharesIssuedForNetCashProceedsOfATMOffering_01a15582-4be1-7959-a372-2ebbbff0a534" xlink:href="xtia-20260630.xsd#xtia_StockIssuedDuringPeriodCommonSharesIssuedForNetCashProceedsOfATMOffering"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019f660f-69f5-74ca-8ab9-8977cb5a1a4e" xlink:to="loc_xtia_StockIssuedDuringPeriodCommonSharesIssuedForNetCashProceedsOfATMOffering_01a15582-4be1-7959-a372-2ebbbff0a534" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_StockIssuedDuringCommonSharesIssuedForNetCashProceedsOfATMOffering_01a15582-4be1-705e-9a43-820654c17584" xlink:href="xtia-20260630.xsd#xtia_StockIssuedDuringCommonSharesIssuedForNetCashProceedsOfATMOffering"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019f660f-69f5-74ca-8ab9-8977cb5a1a4e" xlink:to="loc_xtia_StockIssuedDuringCommonSharesIssuedForNetCashProceedsOfATMOffering_01a15582-4be1-705e-9a43-820654c17584" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_StockIssuedDuringPeriodSharesNetCashProceedsOfPublicOfferings_01a15582-4be1-7859-88f6-bf649f76338b" xlink:href="xtia-20260630.xsd#xtia_StockIssuedDuringPeriodSharesNetCashProceedsOfPublicOfferings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019f660f-69f5-74ca-8ab9-8977cb5a1a4e" xlink:to="loc_xtia_StockIssuedDuringPeriodSharesNetCashProceedsOfPublicOfferings_01a15582-4be1-7859-88f6-bf649f76338b" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_StockIssuedDuringPeriodValuesNetCashProceedsOfPublicOfferings_01a15582-4be1-7742-be79-2a4bd7d86a50" xlink:href="xtia-20260630.xsd#xtia_StockIssuedDuringPeriodValuesNetCashProceedsOfPublicOfferings"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019f660f-69f5-74ca-8ab9-8977cb5a1a4e" xlink:to="loc_xtia_StockIssuedDuringPeriodValuesNetCashProceedsOfPublicOfferings_01a15582-4be1-7742-be79-2a4bd7d86a50" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_01a15582-4be1-70d3-b6bd-3306705402df" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019f660f-69f5-74ca-8ab9-8977cb5a1a4e" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_01a15582-4be1-70d3-b6bd-3306705402df" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities_01a15582-4be1-76d5-bf69-94fa23609cb5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019f660f-69f5-74ca-8ab9-8977cb5a1a4e" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities_01a15582-4be1-76d5-bf69-94fa23609cb5" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_StockIssuedDuringPeriodSharesCommonSharesIssuedForCashlessExerciseOfWarrantsAndOptions_01a15582-4be1-7615-b4a7-6ae396ebd609" xlink:href="xtia-20260630.xsd#xtia_StockIssuedDuringPeriodSharesCommonSharesIssuedForCashlessExerciseOfWarrantsAndOptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019f660f-69f5-74ca-8ab9-8977cb5a1a4e" xlink:to="loc_xtia_StockIssuedDuringPeriodSharesCommonSharesIssuedForCashlessExerciseOfWarrantsAndOptions_01a15582-4be1-7615-b4a7-6ae396ebd609" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_StockIssuedDuringPeriodValueCommonSharesIssuedForCashlessExerciseOfWarrantsAndOptions_01a15582-4be1-7b6a-90c0-6030b7232b8e" xlink:href="xtia-20260630.xsd#xtia_StockIssuedDuringPeriodValueCommonSharesIssuedForCashlessExerciseOfWarrantsAndOptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019f660f-69f5-74ca-8ab9-8977cb5a1a4e" xlink:to="loc_xtia_StockIssuedDuringPeriodValueCommonSharesIssuedForCashlessExerciseOfWarrantsAndOptions_01a15582-4be1-7b6a-90c0-6030b7232b8e" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_StockIssuedDuringPeriodSharesRedemptionOfPreferredStock_01a15582-4be1-75a9-ae96-9507781f9adb" xlink:href="xtia-20260630.xsd#xtia_StockIssuedDuringPeriodSharesRedemptionOfPreferredStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019f660f-69f5-74ca-8ab9-8977cb5a1a4e" xlink:to="loc_xtia_StockIssuedDuringPeriodSharesRedemptionOfPreferredStock_01a15582-4be1-75a9-ae96-9507781f9adb" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_StockIssuedDuringPeriodValueRedemptionOfPreferredStock_01a15582-4be1-7824-abe1-4dec35583ab5" xlink:href="xtia-20260630.xsd#xtia_StockIssuedDuringPeriodValueRedemptionOfPreferredStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019f660f-69f5-74ca-8ab9-8977cb5a1a4e" xlink:to="loc_xtia_StockIssuedDuringPeriodValueRedemptionOfPreferredStock_01a15582-4be1-7824-abe1-4dec35583ab5" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CumulativeTranslationAdjustmentNetOfTaxPeriodIncreaseDecrease_01a15582-4be1-75f4-8c02-de372fbb9a75" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CumulativeTranslationAdjustmentNetOfTaxPeriodIncreaseDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019f660f-69f5-74ca-8ab9-8977cb5a1a4e" xlink:to="loc_us-gaap_CumulativeTranslationAdjustmentNetOfTaxPeriodIncreaseDecrease_01a15582-4be1-75f4-8c02-de372fbb9a75" xlink:type="arc" order="23"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesOther_01a15582-4be1-78e5-9fb8-7b524b25367f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019f660f-69f5-74ca-8ab9-8977cb5a1a4e" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesOther_01a15582-4be1-78e5-9fb8-7b524b25367f" xlink:type="arc" order="24"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueOther_01a15582-4be1-74b3-a946-422b406cc3dc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodValueOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019f660f-69f5-74ca-8ab9-8977cb5a1a4e" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueOther_01a15582-4be1-74b3-a946-422b406cc3dc" xlink:type="arc" order="25"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesOutstanding_019f660f-69f5-782d-9562-1fcd321203a5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_019f660f-69f5-79dc-899e-51e9af05b440" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.xtiaircraft.com/role/DescriptionofBusinessandOrganizationDetails" xlink:type="simple" xlink:href="xtia-20260630.xsd#DescriptionofBusinessandOrganizationDetails"/>
  <link:definitionLink xlink:role="http://www.xtiaircraft.com/role/DescriptionofBusinessandOrganizationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProductInformationLineItems_019f660f-69f5-7f7b-ba79-54f9b7eb58a8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProductInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_DescriptionofBusinessandOrganizationDetailsTable_019f660f-69f5-76d9-9bb7-4b09194956b0" xlink:href="xtia-20260630.xsd#xtia_DescriptionofBusinessandOrganizationDetailsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ProductInformationLineItems_019f660f-69f5-7f7b-ba79-54f9b7eb58a8" xlink:to="loc_xtia_DescriptionofBusinessandOrganizationDetailsTable_019f660f-69f5-76d9-9bb7-4b09194956b0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_01a08162-7347-79b2-b73d-53d4edc4257a" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_xtia_DescriptionofBusinessandOrganizationDetailsTable_019f660f-69f5-76d9-9bb7-4b09194956b0" xlink:to="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_01a08162-7347-79b2-b73d-53d4edc4257a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_01a08162-7347-79b2-b73d-53d4edc4257a_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_01a08162-7347-79b2-b73d-53d4edc4257a" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_01a08162-7347-79b2-b73d-53d4edc4257a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EquityMethodInvesteeNameDomain_01a08162-7347-746b-93b5-3ff01fbb2a86" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_EquityMethodInvesteeNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_01a08162-7347-79b2-b73d-53d4edc4257a" xlink:to="loc_srt_EquityMethodInvesteeNameDomain_01a08162-7347-746b-93b5-3ff01fbb2a86" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_DroneHoldingsSubsidiaryMember_01a08162-7347-7c9d-9610-3656c4527269" xlink:href="xtia-20260630.xsd#xtia_DroneHoldingsSubsidiaryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_EquityMethodInvesteeNameDomain_01a08162-7347-746b-93b5-3ff01fbb2a86" xlink:to="loc_xtia_DroneHoldingsSubsidiaryMember_01a08162-7347-7c9d-9610-3656c4527269" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_01a08162-7347-74ef-8c1a-d7bc3e19a076" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_xtia_DescriptionofBusinessandOrganizationDetailsTable_019f660f-69f5-76d9-9bb7-4b09194956b0" xlink:to="loc_us-gaap_StatementClassOfStockAxis_01a08162-7347-74ef-8c1a-d7bc3e19a076" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_01a08162-7347-74ef-8c1a-d7bc3e19a076_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_01a08162-7347-74ef-8c1a-d7bc3e19a076" xlink:to="loc_us-gaap_ClassOfStockDomain_01a08162-7347-74ef-8c1a-d7bc3e19a076_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_01a08162-7347-7ee1-aa67-f43ba3dc4f6c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_01a08162-7347-74ef-8c1a-d7bc3e19a076" xlink:to="loc_us-gaap_ClassOfStockDomain_01a08162-7347-7ee1-aa67-f43ba3dc4f6c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_ClassAUnitsMember_01a08162-7347-7dfe-9f00-d80ce4a89223" xlink:href="xtia-20260630.xsd#xtia_ClassAUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_01a08162-7347-7ee1-aa67-f43ba3dc4f6c" xlink:to="loc_xtia_ClassAUnitsMember_01a08162-7347-7dfe-9f00-d80ce4a89223" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_ClassBUnitsMember_01a08162-7347-71bc-bd27-bcf5b464e436" xlink:href="xtia-20260630.xsd#xtia_ClassBUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_01a08162-7347-7ee1-aa67-f43ba3dc4f6c" xlink:to="loc_xtia_ClassBUnitsMember_01a08162-7347-71bc-bd27-bcf5b464e436" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_01a08162-7347-78c8-8112-beaa722d1e98" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_xtia_DescriptionofBusinessandOrganizationDetailsTable_019f660f-69f5-76d9-9bb7-4b09194956b0" xlink:to="loc_us-gaap_DebtInstrumentAxis_01a08162-7347-78c8-8112-beaa722d1e98" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_01a08162-7347-78c8-8112-beaa722d1e98_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_01a08162-7347-78c8-8112-beaa722d1e98" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_01a08162-7347-78c8-8112-beaa722d1e98_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_01a08162-7347-729c-ab73-af761055c83e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_01a08162-7347-78c8-8112-beaa722d1e98" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_01a08162-7347-729c-ab73-af761055c83e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_AcquisitionRelatedPromissoryNotesMember_01a08162-7347-7b41-adb7-0ea8a70cfaba" xlink:href="xtia-20260630.xsd#xtia_AcquisitionRelatedPromissoryNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_01a08162-7347-729c-ab73-af761055c83e" xlink:to="loc_xtia_AcquisitionRelatedPromissoryNotesMember_01a08162-7347-7b41-adb7-0ea8a70cfaba" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfReportableSegments_01a08162-7347-7d00-84f7-434b9c6b550a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NumberOfReportableSegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductInformationLineItems_019f660f-69f5-7f7b-ba79-54f9b7eb58a8" xlink:to="loc_us-gaap_NumberOfReportableSegments_01a08162-7347-7d00-84f7-434b9c6b550a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_01a08162-7347-7abd-bfea-d0ae11c22b05" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityMethodInvestmentOwnershipPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductInformationLineItems_019f660f-69f5-7f7b-ba79-54f9b7eb58a8" xlink:to="loc_us-gaap_EquityMethodInvestmentOwnershipPercentage_01a08162-7347-7abd-bfea-d0ae11c22b05" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_01a1211d-eee7-7504-94ef-0681ed392b16" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductInformationLineItems_019f660f-69f5-7f7b-ba79-54f9b7eb58a8" xlink:to="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_01a1211d-eee7-7504-94ef-0681ed392b16" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_01a1211d-eee7-7b7f-b4df-57faf671141a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductInformationLineItems_019f660f-69f5-7f7b-ba79-54f9b7eb58a8" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_01a1211d-eee7-7b7f-b4df-57faf671141a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_01a1211d-eee7-7c47-8989-355da1c7b1a1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductInformationLineItems_019f660f-69f5-7f7b-ba79-54f9b7eb58a8" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_01a1211d-eee7-7c47-8989-355da1c7b1a1" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_01a1211d-eee7-76df-8fa2-5e1f09781b3a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductInformationLineItems_019f660f-69f5-7f7b-ba79-54f9b7eb58a8" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_01a1211d-eee7-76df-8fa2-5e1f09781b3a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtNoncurrent_01a08162-7347-764c-aaa7-0d3b89cd546d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermDebtNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductInformationLineItems_019f660f-69f5-7f7b-ba79-54f9b7eb58a8" xlink:to="loc_us-gaap_LongTermDebtNoncurrent_01a08162-7347-764c-aaa7-0d3b89cd546d" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.xtiaircraft.com/role/SummaryofSignificantAccountingPoliciesNarrativeDetails" xlink:type="simple" xlink:href="xtia-20260630.xsd#SummaryofSignificantAccountingPoliciesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.xtiaircraft.com/role/SummaryofSignificantAccountingPoliciesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_019f660f-69f5-7d3d-874a-884981af2348" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_SummaryofSignificantAccountingPoliciesDetailsTable_019f660f-69f5-749d-b5ab-d1bedbde2f17" xlink:href="xtia-20260630.xsd#xtia_SummaryofSignificantAccountingPoliciesDetailsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_019f660f-69f5-7d3d-874a-884981af2348" xlink:to="loc_xtia_SummaryofSignificantAccountingPoliciesDetailsTable_019f660f-69f5-749d-b5ab-d1bedbde2f17" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019f660f-69f5-7b5d-be34-76ff523fd95e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_xtia_SummaryofSignificantAccountingPoliciesDetailsTable_019f660f-69f5-749d-b5ab-d1bedbde2f17" xlink:to="loc_us-gaap_DebtInstrumentAxis_019f660f-69f5-7b5d-be34-76ff523fd95e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019f660f-69f5-7b5d-be34-76ff523fd95e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_019f660f-69f5-7b5d-be34-76ff523fd95e" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019f660f-69f5-7b5d-be34-76ff523fd95e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019f660f-69f5-7000-8238-0a5451ec11fb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_019f660f-69f5-7b5d-be34-76ff523fd95e" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019f660f-69f5-7000-8238-0a5451ec11fb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_ValkyrieConvertiblePromissoryNoteMember_019f660f-69f5-74d1-ab67-92958ff42b77" xlink:href="xtia-20260630.xsd#xtia_ValkyrieConvertiblePromissoryNoteMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019f660f-69f5-7000-8238-0a5451ec11fb" xlink:to="loc_xtia_ValkyrieConvertiblePromissoryNoteMember_019f660f-69f5-74d1-ab67-92958ff42b77" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_01a000dd-51f3-7da4-8fc5-0aa559ae437d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_xtia_SummaryofSignificantAccountingPoliciesDetailsTable_019f660f-69f5-749d-b5ab-d1bedbde2f17" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_01a000dd-51f3-7da4-8fc5-0aa559ae437d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_01a000dd-51f3-7da4-8fc5-0aa559ae437d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_01a000dd-51f3-7da4-8fc5-0aa559ae437d" xlink:to="loc_us-gaap_RelatedPartyDomain_01a000dd-51f3-7da4-8fc5-0aa559ae437d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_01a000dd-51f3-7a39-98ed-20b70dd5c74f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_01a000dd-51f3-7da4-8fc5-0aa559ae437d" xlink:to="loc_us-gaap_RelatedPartyDomain_01a000dd-51f3-7a39-98ed-20b70dd5c74f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_InpixonMember_01a000dd-51f3-760c-b1e0-65c137807aa1" xlink:href="xtia-20260630.xsd#xtia_InpixonMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_01a000dd-51f3-7a39-98ed-20b70dd5c74f" xlink:to="loc_xtia_InpixonMember_01a000dd-51f3-760c-b1e0-65c137807aa1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashCurrent_01a000dc-b5d2-7850-b9ba-74a255a25ec8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestrictedCashCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_019f660f-69f5-7d3d-874a-884981af2348" xlink:to="loc_us-gaap_RestrictedCashCurrent_01a000dc-b5d2-7850-b9ba-74a255a25ec8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllowanceForDoubtfulAccountsReceivable_019f660f-69f5-7d2a-a8d0-81ce9d3762f8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AllowanceForDoubtfulAccountsReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_019f660f-69f5-7d3d-874a-884981af2348" xlink:to="loc_us-gaap_AllowanceForDoubtfulAccountsReceivable_019f660f-69f5-7d2a-a8d0-81ce9d3762f8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NotesReceivableFairValueDisclosure_01a000e1-8463-7b3c-98e8-fd932ab9deb5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NotesReceivableFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_019f660f-69f5-7d3d-874a-884981af2348" xlink:to="loc_us-gaap_NotesReceivableFairValueDisclosure_01a000e1-8463-7b3c-98e8-fd932ab9deb5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_NoteReceivableAccruedInterestRate_01a000e1-8463-7555-a3fc-5ae42b258cb3" xlink:href="xtia-20260630.xsd#xtia_NoteReceivableAccruedInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_019f660f-69f5-7d3d-874a-884981af2348" xlink:to="loc_xtia_NoteReceivableAccruedInterestRate_01a000e1-8463-7555-a3fc-5ae42b258cb3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_NoteReceivableUnwindOptionPeriod_01a154c1-48e9-7687-b9b2-96c1b34e98d3" xlink:href="xtia-20260630.xsd#xtia_NoteReceivableUnwindOptionPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleLineItems_019f660f-69f5-7d3d-874a-884981af2348" xlink:to="loc_xtia_NoteReceivableUnwindOptionPeriod_01a154c1-48e9-7687-b9b2-96c1b34e98d3" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.xtiaircraft.com/role/SummaryofSignificantAccountingPoliciesScheduleofConcentrationofRiskbyRiskFactorDetails" xlink:type="simple" xlink:href="xtia-20260630.xsd#SummaryofSignificantAccountingPoliciesScheduleofConcentrationofRiskbyRiskFactorDetails"/>
  <link:definitionLink xlink:role="http://www.xtiaircraft.com/role/SummaryofSignificantAccountingPoliciesScheduleofConcentrationofRiskbyRiskFactorDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskLineItems_019f660f-6aa0-7b4b-a0c7-5465ef55acde" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTable_019f660f-69f5-7804-97ea-4619eda9a266" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_019f660f-6aa0-7b4b-a0c7-5465ef55acde" xlink:to="loc_us-gaap_ConcentrationRiskTable_019f660f-69f5-7804-97ea-4619eda9a266" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_019f660f-69f5-737e-bbce-3d79685577ae" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_019f660f-69f5-7804-97ea-4619eda9a266" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_019f660f-69f5-737e-bbce-3d79685577ae" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_019f660f-69f5-737e-bbce-3d79685577ae_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_019f660f-69f5-737e-bbce-3d79685577ae" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_019f660f-69f5-737e-bbce-3d79685577ae_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_019f660f-69f5-7e31-beb3-0f6334291916" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_019f660f-69f5-737e-bbce-3d79685577ae" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_019f660f-69f5-7e31-beb3-0f6334291916" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerConcentrationRiskMember_019f660f-69f5-7050-848c-67c5edf44199" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CustomerConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_019f660f-69f5-7e31-beb3-0f6334291916" xlink:to="loc_us-gaap_CustomerConcentrationRiskMember_019f660f-69f5-7050-848c-67c5edf44199" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis_019f660f-69f5-7570-9ff1-5775ed337030" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MajorCustomersAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_019f660f-69f5-7804-97ea-4619eda9a266" xlink:to="loc_srt_MajorCustomersAxis_019f660f-69f5-7570-9ff1-5775ed337030" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_019f660f-69f5-7570-9ff1-5775ed337030_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MajorCustomersAxis_019f660f-69f5-7570-9ff1-5775ed337030" xlink:to="loc_srt_NameOfMajorCustomerDomain_019f660f-69f5-7570-9ff1-5775ed337030_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_019f660f-69f5-7535-b074-03af4cc3289b" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MajorCustomersAxis_019f660f-69f5-7570-9ff1-5775ed337030" xlink:to="loc_srt_NameOfMajorCustomerDomain_019f660f-69f5-7535-b074-03af4cc3289b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_CustomerAMember_019f660f-69f5-7939-8158-034ac3ac7a56" xlink:href="xtia-20260630.xsd#xtia_CustomerAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019f660f-69f5-7535-b074-03af4cc3289b" xlink:to="loc_xtia_CustomerAMember_019f660f-69f5-7939-8158-034ac3ac7a56" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_CustomerBMember_019f660f-69f5-72de-8ed6-278ea847ca16" xlink:href="xtia-20260630.xsd#xtia_CustomerBMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019f660f-69f5-7535-b074-03af4cc3289b" xlink:to="loc_xtia_CustomerBMember_019f660f-69f5-72de-8ed6-278ea847ca16" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_CustomerCMember_019fcd9b-a209-70a8-9be6-0879d7be24d2" xlink:href="xtia-20260630.xsd#xtia_CustomerCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019f660f-69f5-7535-b074-03af4cc3289b" xlink:to="loc_xtia_CustomerCMember_019fcd9b-a209-70a8-9be6-0879d7be24d2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_VendorAMember_019f660f-69f5-71e6-95da-793d14340a83" xlink:href="xtia-20260630.xsd#xtia_VendorAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019f660f-69f5-7535-b074-03af4cc3289b" xlink:to="loc_xtia_VendorAMember_019f660f-69f5-71e6-95da-793d14340a83" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_VendorBMember_019f660f-69f5-7c64-9de9-61b0bf43641a" xlink:href="xtia-20260630.xsd#xtia_VendorBMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019f660f-69f5-7535-b074-03af4cc3289b" xlink:to="loc_xtia_VendorBMember_019f660f-69f5-7c64-9de9-61b0bf43641a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_VendorCMember_019fcda0-9ef2-7e3c-a65a-882ac3577a35" xlink:href="xtia-20260630.xsd#xtia_VendorCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019f660f-69f5-7535-b074-03af4cc3289b" xlink:to="loc_xtia_VendorCMember_019fcda0-9ef2-7e3c-a65a-882ac3577a35" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_VendorDMember_019fcda0-c11d-7cc8-8dc7-aedaa0e1cca8" xlink:href="xtia-20260630.xsd#xtia_VendorDMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019f660f-69f5-7535-b074-03af4cc3289b" xlink:to="loc_xtia_VendorDMember_019fcda0-c11d-7cc8-8dc7-aedaa0e1cca8" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_VendorEMember_019fcda0-eb83-7275-82ae-f5660941e6ca" xlink:href="xtia-20260630.xsd#xtia_VendorEMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019f660f-69f5-7535-b074-03af4cc3289b" xlink:to="loc_xtia_VendorEMember_019fcda0-eb83-7275-82ae-f5660941e6ca" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_VendorFMember_019fcda1-1225-7dee-bc60-d6e5ddb3e734" xlink:href="xtia-20260630.xsd#xtia_VendorFMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019f660f-69f5-7535-b074-03af4cc3289b" xlink:to="loc_xtia_VendorFMember_019fcda1-1225-7dee-bc60-d6e5ddb3e734" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019f660f-69f5-7446-9948-6b18187d833e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_019f660f-69f5-7804-97ea-4619eda9a266" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019f660f-69f5-7446-9948-6b18187d833e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019f660f-69f5-7446-9948-6b18187d833e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019f660f-69f5-7446-9948-6b18187d833e" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019f660f-69f5-7446-9948-6b18187d833e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019f660f-69f5-7499-9b88-3216ba600935" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019f660f-69f5-7446-9948-6b18187d833e" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019f660f-69f5-7499-9b88-3216ba600935" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SalesRevenueNetMember_019f660f-69f5-7e65-a167-1b7ecb36500a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SalesRevenueNetMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019f660f-69f5-7499-9b88-3216ba600935" xlink:to="loc_us-gaap_SalesRevenueNetMember_019f660f-69f5-7e65-a167-1b7ecb36500a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableMember_019f660f-69f5-7f5c-b5cd-4fc23e1d21f7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccountsReceivableMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019f660f-69f5-7499-9b88-3216ba600935" xlink:to="loc_us-gaap_AccountsReceivableMember_019f660f-69f5-7f5c-b5cd-4fc23e1d21f7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_PurchasesMember_019f660f-6aa0-7826-969d-6362118c69b8" xlink:href="xtia-20260630.xsd#xtia_PurchasesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019f660f-69f5-7499-9b88-3216ba600935" xlink:to="loc_xtia_PurchasesMember_019f660f-6aa0-7826-969d-6362118c69b8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableMember_019f660f-6aa0-7741-9398-354bc8bb8434" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccountsPayableMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019f660f-69f5-7499-9b88-3216ba600935" xlink:to="loc_us-gaap_AccountsPayableMember_019f660f-6aa0-7741-9398-354bc8bb8434" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_019f660f-6aa0-78c7-8196-90944d198b9e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskPercentage1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_019f660f-6aa0-7b4b-a0c7-5465ef55acde" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_019f660f-6aa0-78c7-8196-90944d198b9e" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.xtiaircraft.com/role/DisaggregationofRevenueScheduleofDisaggregationofRevenueDetails" xlink:type="simple" xlink:href="xtia-20260630.xsd#DisaggregationofRevenueScheduleofDisaggregationofRevenueDetails"/>
  <link:definitionLink xlink:role="http://www.xtiaircraft.com/role/DisaggregationofRevenueScheduleofDisaggregationofRevenueDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_019f660f-6aa0-7764-b078-bd0de7620b2d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_019f660f-6aa0-743f-906b-0827f2ca9a07" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019f660f-6aa0-7764-b078-bd0de7620b2d" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_019f660f-6aa0-743f-906b-0827f2ca9a07" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOperatingActivitiesSegmentAxis_019f660f-6aa0-7a15-8406-3e069ae2c625" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementOperatingActivitiesSegmentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019f660f-6aa0-743f-906b-0827f2ca9a07" xlink:to="loc_us-gaap_StatementOperatingActivitiesSegmentAxis_019f660f-6aa0-7a15-8406-3e069ae2c625" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentOperatingActivitiesDomain_019f660f-6aa0-7a15-8406-3e069ae2c625_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentOperatingActivitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementOperatingActivitiesSegmentAxis_019f660f-6aa0-7a15-8406-3e069ae2c625" xlink:to="loc_us-gaap_SegmentOperatingActivitiesDomain_019f660f-6aa0-7a15-8406-3e069ae2c625_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentOperatingActivitiesDomain_019f660f-6aa0-788a-995a-b8b27f1b5a41" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentOperatingActivitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementOperatingActivitiesSegmentAxis_019f660f-6aa0-7a15-8406-3e069ae2c625" xlink:to="loc_us-gaap_SegmentOperatingActivitiesDomain_019f660f-6aa0-788a-995a-b8b27f1b5a41" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentContinuingOperationsMember_019f660f-6aa0-725c-8db3-8a3746813ae6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentContinuingOperationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentOperatingActivitiesDomain_019f660f-6aa0-788a-995a-b8b27f1b5a41" xlink:to="loc_us-gaap_SegmentContinuingOperationsMember_019f660f-6aa0-725c-8db3-8a3746813ae6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_019f660f-6aa0-75cf-b55b-5b1226280800" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019f660f-6aa0-743f-906b-0827f2ca9a07" xlink:to="loc_srt_ProductOrServiceAxis_019f660f-6aa0-75cf-b55b-5b1226280800" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019f660f-6aa0-75cf-b55b-5b1226280800_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_019f660f-6aa0-75cf-b55b-5b1226280800" xlink:to="loc_srt_ProductsAndServicesDomain_019f660f-6aa0-75cf-b55b-5b1226280800_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019f660f-6aa0-76c3-858a-a22cab8345c2" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_019f660f-6aa0-75cf-b55b-5b1226280800" xlink:to="loc_srt_ProductsAndServicesDomain_019f660f-6aa0-76c3-858a-a22cab8345c2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_WholesaleMember_019f660f-6aa0-78fd-98ec-458c489d010f" xlink:href="xtia-20260630.xsd#xtia_WholesaleMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019f660f-6aa0-76c3-858a-a22cab8345c2" xlink:to="loc_xtia_WholesaleMember_019f660f-6aa0-78fd-98ec-458c489d010f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_DirectSalesMember_019f660f-6aa0-7b8f-ad09-0902eadac53d" xlink:href="xtia-20260630.xsd#xtia_DirectSalesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019f660f-6aa0-76c3-858a-a22cab8345c2" xlink:to="loc_xtia_DirectSalesMember_019f660f-6aa0-7b8f-ad09-0902eadac53d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetailMember_019f660f-6aa0-7a52-a712-3aa54491de4f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RetailMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019f660f-6aa0-76c3-858a-a22cab8345c2" xlink:to="loc_us-gaap_RetailMember_019f660f-6aa0-7a52-a712-3aa54491de4f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerDurationAxis_019f660f-6aa0-7f80-b9f9-eb29385c0c90" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ContractWithCustomerDurationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019f660f-6aa0-743f-906b-0827f2ca9a07" xlink:to="loc_us-gaap_ContractWithCustomerDurationAxis_019f660f-6aa0-7f80-b9f9-eb29385c0c90" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerDurationDomain_019f660f-6aa0-7f80-b9f9-eb29385c0c90_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ContractWithCustomerDurationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ContractWithCustomerDurationAxis_019f660f-6aa0-7f80-b9f9-eb29385c0c90" xlink:to="loc_us-gaap_ContractWithCustomerDurationDomain_019f660f-6aa0-7f80-b9f9-eb29385c0c90_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerDurationDomain_019f660f-6aa0-73e7-8c01-476633840282" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ContractWithCustomerDurationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ContractWithCustomerDurationAxis_019f660f-6aa0-7f80-b9f9-eb29385c0c90" xlink:to="loc_us-gaap_ContractWithCustomerDurationDomain_019f660f-6aa0-73e7-8c01-476633840282" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermContractWithCustomerMember_019f660f-6aa0-7d28-ad81-c5b556c63af3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortTermContractWithCustomerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerDurationDomain_019f660f-6aa0-73e7-8c01-476633840282" xlink:to="loc_us-gaap_ShortTermContractWithCustomerMember_019f660f-6aa0-7d28-ad81-c5b556c63af3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_019f660f-6aa0-7a4a-ba6b-1810e3687d80" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019f660f-6aa0-7764-b078-bd0de7620b2d" xlink:to="loc_us-gaap_Revenues_019f660f-6aa0-7a4a-ba6b-1810e3687d80" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.xtiaircraft.com/role/GoodwillandIntangibleAssetsScheduleofIntangibleAssetsDetails" xlink:type="simple" xlink:href="xtia-20260630.xsd#GoodwillandIntangibleAssetsScheduleofIntangibleAssetsDetails"/>
  <link:definitionLink xlink:role="http://www.xtiaircraft.com/role/GoodwillandIntangibleAssetsScheduleofIntangibleAssetsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_019f660f-6aa0-7bf8-b9b1-1ebede688171" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_019f660f-6aa0-7c3b-b871-11531376a1ad" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_019f660f-6aa0-7bf8-b9b1-1ebede688171" xlink:to="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_019f660f-6aa0-7c3b-b871-11531376a1ad" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019f660f-6aa0-7565-a62b-15ef0da3cf18" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_019f660f-6aa0-7c3b-b871-11531376a1ad" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019f660f-6aa0-7565-a62b-15ef0da3cf18" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019f660f-6aa0-7565-a62b-15ef0da3cf18_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019f660f-6aa0-7565-a62b-15ef0da3cf18" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019f660f-6aa0-7565-a62b-15ef0da3cf18_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019f660f-6aa0-7c0b-879e-7331ff586830" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019f660f-6aa0-7565-a62b-15ef0da3cf18" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019f660f-6aa0-7c0b-879e-7331ff586830" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PatentsMember_019f660f-6aa0-71e4-a4ab-7fce0c70d0c8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PatentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019f660f-6aa0-7c0b-879e-7331ff586830" xlink:to="loc_us-gaap_PatentsMember_019f660f-6aa0-71e4-a4ab-7fce0c70d0c8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TrademarksAndTradeNamesMember_019f660f-6aa0-7004-bc7b-2ad05b334ed7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TrademarksAndTradeNamesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019f660f-6aa0-7c0b-879e-7331ff586830" xlink:to="loc_us-gaap_TrademarksAndTradeNamesMember_019f660f-6aa0-7004-bc7b-2ad05b334ed7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_019f660f-6aa0-76ee-b60c-640d47c06aff" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019f660f-6aa0-7c0b-879e-7331ff586830" xlink:to="loc_us-gaap_CustomerRelationshipsMember_019f660f-6aa0-76ee-b60c-640d47c06aff" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_019f660f-6aa0-776e-b03e-2e9ad6277fe1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_019f660f-6aa0-7bf8-b9b1-1ebede688171" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_019f660f-6aa0-776e-b03e-2e9ad6277fe1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_019f660f-6aa0-74ad-bf36-36e2d1c66e6e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_019f660f-6aa0-7bf8-b9b1-1ebede688171" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_019f660f-6aa0-74ad-bf36-36e2d1c66e6e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_019f660f-6aa0-7562-9d97-05976bfaa753" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_019f660f-6aa0-7bf8-b9b1-1ebede688171" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsNet_019f660f-6aa0-7562-9d97-05976bfaa753" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetWeightedAveragePeriodBeforeNextRenewalOrExtension_019f660f-6aa0-705f-b9f8-0db8b58e0a45" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetWeightedAveragePeriodBeforeNextRenewalOrExtension"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_019f660f-6aa0-7bf8-b9b1-1ebede688171" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetWeightedAveragePeriodBeforeNextRenewalOrExtension_019f660f-6aa0-705f-b9f8-0db8b58e0a45" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.xtiaircraft.com/role/OtherBalanceSheetInformationScheduleofInventoryDetails" xlink:type="simple" xlink:href="xtia-20260630.xsd#OtherBalanceSheetInformationScheduleofInventoryDetails"/>
  <link:definitionLink xlink:role="http://www.xtiaircraft.com/role/OtherBalanceSheetInformationScheduleofInventoryDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryLineItems_019f660f-6aa0-70bd-a030-b8efadd7e916" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InventoryLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryCurrentTable_019f660f-6aa0-7baf-9e52-78d71e78a4d4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InventoryCurrentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_InventoryLineItems_019f660f-6aa0-70bd-a030-b8efadd7e916" xlink:to="loc_us-gaap_InventoryCurrentTable_019f660f-6aa0-7baf-9e52-78d71e78a4d4" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis_019f660f-6aa0-7381-96af-199a1e4f7e6e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_InventoryCurrentTable_019f660f-6aa0-7baf-9e52-78d71e78a4d4" xlink:to="loc_us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis_019f660f-6aa0-7381-96af-199a1e4f7e6e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain_019f660f-6aa0-7381-96af-199a1e4f7e6e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis_019f660f-6aa0-7381-96af-199a1e4f7e6e" xlink:to="loc_us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain_019f660f-6aa0-7381-96af-199a1e4f7e6e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain_019f660f-6aa0-7668-b206-d48e299c0695" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis_019f660f-6aa0-7381-96af-199a1e4f7e6e" xlink:to="loc_us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain_019f660f-6aa0-7668-b206-d48e299c0695" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_DronesMember_019f660f-6aa0-7082-880d-3778e413e327" xlink:href="xtia-20260630.xsd#xtia_DronesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain_019f660f-6aa0-7668-b206-d48e299c0695" xlink:to="loc_xtia_DronesMember_019f660f-6aa0-7082-880d-3778e413e327" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_AccessoriesMember_019f660f-6aa0-7f8c-ab47-3a606a344347" xlink:href="xtia-20260630.xsd#xtia_AccessoriesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain_019f660f-6aa0-7668-b206-d48e299c0695" xlink:to="loc_xtia_AccessoriesMember_019f660f-6aa0-7f8c-ab47-3a606a344347" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_ServicePartsAndComponentsMember_019f660f-6aa0-781e-a189-8f25ef3007e1" xlink:href="xtia-20260630.xsd#xtia_ServicePartsAndComponentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain_019f660f-6aa0-7668-b206-d48e299c0695" xlink:to="loc_xtia_ServicePartsAndComponentsMember_019f660f-6aa0-781e-a189-8f25ef3007e1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryNet_019f660f-6aa0-7263-afa2-0f90805ea133" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InventoryNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InventoryLineItems_019f660f-6aa0-70bd-a030-b8efadd7e916" xlink:to="loc_us-gaap_InventoryNet_019f660f-6aa0-7263-afa2-0f90805ea133" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.xtiaircraft.com/role/DebtScheduleofOutstandingDebtDetails" xlink:type="simple" xlink:href="xtia-20260630.xsd#DebtScheduleofOutstandingDebtDetails"/>
  <link:definitionLink xlink:role="http://www.xtiaircraft.com/role/DebtScheduleofOutstandingDebtDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019f660f-6aa0-74bd-a863-7bf350dd1a7b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_DebtScheduleofOutstandingDebtDetailsTable_019f660f-6aa0-7510-8d28-c92e0b51d816" xlink:href="xtia-20260630.xsd#xtia_DebtScheduleofOutstandingDebtDetailsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f660f-6aa0-74bd-a863-7bf350dd1a7b" xlink:to="loc_xtia_DebtScheduleofOutstandingDebtDetailsTable_019f660f-6aa0-7510-8d28-c92e0b51d816" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019f660f-6aa0-7909-82a1-26019372db2b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_xtia_DebtScheduleofOutstandingDebtDetailsTable_019f660f-6aa0-7510-8d28-c92e0b51d816" xlink:to="loc_us-gaap_DebtInstrumentAxis_019f660f-6aa0-7909-82a1-26019372db2b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019f660f-6aa0-7909-82a1-26019372db2b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_019f660f-6aa0-7909-82a1-26019372db2b" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019f660f-6aa0-7909-82a1-26019372db2b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019f660f-6aa0-7957-a920-15e85e8ddf2c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_019f660f-6aa0-7909-82a1-26019372db2b" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019f660f-6aa0-7957-a920-15e85e8ddf2c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_AcquisitionRelatedPromissoryNotesMember_019fcdb0-55de-79f2-93cd-8f3a375676b7" xlink:href="xtia-20260630.xsd#xtia_AcquisitionRelatedPromissoryNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019f660f-6aa0-7957-a920-15e85e8ddf2c" xlink:to="loc_xtia_AcquisitionRelatedPromissoryNotesMember_019fcdb0-55de-79f2-93cd-8f3a375676b7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_AssetBasedRevolvingLineOfCreditDroneNerdsMember_019f660f-6aa0-7153-9ee5-60edcd2cec46" xlink:href="xtia-20260630.xsd#xtia_AssetBasedRevolvingLineOfCreditDroneNerdsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019f660f-6aa0-7957-a920-15e85e8ddf2c" xlink:to="loc_xtia_AssetBasedRevolvingLineOfCreditDroneNerdsMember_019f660f-6aa0-7153-9ee5-60edcd2cec46" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtNoncurrent_019f660f-6aa0-7426-b32e-64e1a8bd6d41" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermDebtNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019f660f-6aa0-74bd-a863-7bf350dd1a7b" xlink:to="loc_us-gaap_LongTermDebtNoncurrent_019f660f-6aa0-7426-b32e-64e1a8bd6d41" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.xtiaircraft.com/role/DebtNarrativeDetails" xlink:type="simple" xlink:href="xtia-20260630.xsd#DebtNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.xtiaircraft.com/role/DebtNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtLineItems_019f660f-6aa0-75b5-a29b-af3ad7085afb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortTermDebtLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_DebtDetailsTable_019f660f-6aa0-75fe-a37d-65a8d9384ed5" xlink:href="xtia-20260630.xsd#xtia_DebtDetailsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShortTermDebtLineItems_019f660f-6aa0-75b5-a29b-af3ad7085afb" xlink:to="loc_xtia_DebtDetailsTable_019f660f-6aa0-75fe-a37d-65a8d9384ed5" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019f660f-6aa0-7872-ab94-8281d0c2fe51" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_xtia_DebtDetailsTable_019f660f-6aa0-75fe-a37d-65a8d9384ed5" xlink:to="loc_srt_RangeAxis_019f660f-6aa0-7872-ab94-8281d0c2fe51" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019f660f-6aa0-7872-ab94-8281d0c2fe51_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019f660f-6aa0-7872-ab94-8281d0c2fe51" xlink:to="loc_srt_RangeMember_019f660f-6aa0-7872-ab94-8281d0c2fe51_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019f660f-6aa0-7588-835d-37f922f2c730" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019f660f-6aa0-7872-ab94-8281d0c2fe51" xlink:to="loc_srt_RangeMember_019f660f-6aa0-7588-835d-37f922f2c730" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019f660f-6aa0-767b-b581-6781fd83993b" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019f660f-6aa0-7588-835d-37f922f2c730" xlink:to="loc_srt_MinimumMember_019f660f-6aa0-767b-b581-6781fd83993b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019f660f-6aa0-776e-b877-bb91e5724b4f" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019f660f-6aa0-7588-835d-37f922f2c730" xlink:to="loc_srt_MaximumMember_019f660f-6aa0-776e-b877-bb91e5724b4f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019f660f-6aa0-7f5d-9d7b-af09040d4d3b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_xtia_DebtDetailsTable_019f660f-6aa0-75fe-a37d-65a8d9384ed5" xlink:to="loc_us-gaap_DebtInstrumentAxis_019f660f-6aa0-7f5d-9d7b-af09040d4d3b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019f660f-6aa0-7f5d-9d7b-af09040d4d3b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_019f660f-6aa0-7f5d-9d7b-af09040d4d3b" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019f660f-6aa0-7f5d-9d7b-af09040d4d3b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019f660f-6aa0-7578-bc47-98ba10d10d44" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_019f660f-6aa0-7f5d-9d7b-af09040d4d3b" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019f660f-6aa0-7578-bc47-98ba10d10d44" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_AcquisitionRelatedPromissoryNotesMember_019f660f-6aa0-7f9e-a268-c459ad198890" xlink:href="xtia-20260630.xsd#xtia_AcquisitionRelatedPromissoryNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019f660f-6aa0-7578-bc47-98ba10d10d44" xlink:to="loc_xtia_AcquisitionRelatedPromissoryNotesMember_019f660f-6aa0-7f9e-a268-c459ad198890" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_AssetBasedRevolvingLineOfCreditDroneNerdsMember_019fcdb4-148e-7f9e-b133-326890e2b0aa" xlink:href="xtia-20260630.xsd#xtia_AssetBasedRevolvingLineOfCreditDroneNerdsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019f660f-6aa0-7578-bc47-98ba10d10d44" xlink:to="loc_xtia_AssetBasedRevolvingLineOfCreditDroneNerdsMember_019fcdb4-148e-7f9e-b133-326890e2b0aa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementScenarioAxis_019f660f-6aa0-71d4-8c22-85d4ba743f86" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_StatementScenarioAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_xtia_DebtDetailsTable_019f660f-6aa0-75fe-a37d-65a8d9384ed5" xlink:to="loc_srt_StatementScenarioAxis_019f660f-6aa0-71d4-8c22-85d4ba743f86" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_019f660f-6aa0-71d4-8c22-85d4ba743f86_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementScenarioAxis_019f660f-6aa0-71d4-8c22-85d4ba743f86" xlink:to="loc_srt_ScenarioUnspecifiedDomain_019f660f-6aa0-71d4-8c22-85d4ba743f86_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_019f660f-6aa0-71f7-83d9-08270de2530a" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementScenarioAxis_019f660f-6aa0-71d4-8c22-85d4ba743f86" xlink:to="loc_srt_ScenarioUnspecifiedDomain_019f660f-6aa0-71f7-83d9-08270de2530a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioForecastMember_019f660f-6aa0-7d73-b12a-fefec9ae68c8" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ScenarioForecastMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ScenarioUnspecifiedDomain_019f660f-6aa0-71f7-83d9-08270de2530a" xlink:to="loc_srt_ScenarioForecastMember_019f660f-6aa0-7d73-b12a-fefec9ae68c8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_019fcdb2-455a-7716-81d0-c64ddefb7815" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_xtia_DebtDetailsTable_019f660f-6aa0-75fe-a37d-65a8d9384ed5" xlink:to="loc_us-gaap_CreditFacilityAxis_019fcdb2-455a-7716-81d0-c64ddefb7815" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019fcdb2-455a-7716-81d0-c64ddefb7815_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_019fcdb2-455a-7716-81d0-c64ddefb7815" xlink:to="loc_us-gaap_CreditFacilityDomain_019fcdb2-455a-7716-81d0-c64ddefb7815_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019fcdb2-455a-75b6-a5e1-43e1807df95b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_019fcdb2-455a-7716-81d0-c64ddefb7815" xlink:to="loc_us-gaap_CreditFacilityDomain_019fcdb2-455a-75b6-a5e1-43e1807df95b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LetterOfCreditMember_019fcdb2-63ac-728a-a919-f4e53f37fe37" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LetterOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019fcdb2-455a-75b6-a5e1-43e1807df95b" xlink:to="loc_us-gaap_LetterOfCreditMember_019fcdb2-63ac-728a-a919-f4e53f37fe37" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_01a000e8-5d49-7670-a521-2e20d568f2a0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_xtia_DebtDetailsTable_019f660f-6aa0-75fe-a37d-65a8d9384ed5" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_01a000e8-5d49-7670-a521-2e20d568f2a0" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_01a000e8-5d49-7670-a521-2e20d568f2a0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_01a000e8-5d49-7670-a521-2e20d568f2a0" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_01a000e8-5d49-7670-a521-2e20d568f2a0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_01a000e8-5d49-7b65-92d0-a43ead98f8e9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_01a000e8-5d49-7670-a521-2e20d568f2a0" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_01a000e8-5d49-7b65-92d0-a43ead98f8e9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_XTIDroneHoldingsMember_01a000e8-5d49-7242-87ce-392dc6fa688f" xlink:href="xtia-20260630.xsd#xtia_XTIDroneHoldingsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_01a000e8-5d49-7b65-92d0-a43ead98f8e9" xlink:to="loc_xtia_XTIDroneHoldingsMember_01a000e8-5d49-7242-87ce-392dc6fa688f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_01a000e8-5d49-78f4-91a5-a7955c0db0b3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_xtia_DebtDetailsTable_019f660f-6aa0-75fe-a37d-65a8d9384ed5" xlink:to="loc_us-gaap_StatementClassOfStockAxis_01a000e8-5d49-78f4-91a5-a7955c0db0b3" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_01a000e8-5d49-78f4-91a5-a7955c0db0b3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_01a000e8-5d49-78f4-91a5-a7955c0db0b3" xlink:to="loc_us-gaap_ClassOfStockDomain_01a000e8-5d49-78f4-91a5-a7955c0db0b3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_01a000e8-5d49-71a6-ba36-705c3cd56279" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_01a000e8-5d49-78f4-91a5-a7955c0db0b3" xlink:to="loc_us-gaap_ClassOfStockDomain_01a000e8-5d49-71a6-ba36-705c3cd56279" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_NoncontrollingInterestClassBUnitsMember_01a000e8-5d49-7013-ad7b-6055228fe596" xlink:href="xtia-20260630.xsd#xtia_NoncontrollingInterestClassBUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_01a000e8-5d49-71a6-ba36-705c3cd56279" xlink:to="loc_xtia_NoncontrollingInterestClassBUnitsMember_01a000e8-5d49-7013-ad7b-6055228fe596" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_ClassBUnitsMember_01a000e8-5d49-745b-a894-c1a89ea0be74" xlink:href="xtia-20260630.xsd#xtia_ClassBUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_01a000e8-5d49-71a6-ba36-705c3cd56279" xlink:to="loc_xtia_ClassBUnitsMember_01a000e8-5d49-745b-a894-c1a89ea0be74" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_01a01532-f249-708b-b61e-d1ff27d5fc0b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_xtia_DebtDetailsTable_019f660f-6aa0-75fe-a37d-65a8d9384ed5" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_01a01532-f249-708b-b61e-d1ff27d5fc0b" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_01a01532-f249-708b-b61e-d1ff27d5fc0b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_01a01532-f249-708b-b61e-d1ff27d5fc0b" xlink:to="loc_us-gaap_RelatedPartyDomain_01a01532-f249-708b-b61e-d1ff27d5fc0b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_01a01532-f249-70be-b87f-df2046b06ad2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_01a01532-f249-708b-b61e-d1ff27d5fc0b" xlink:to="loc_us-gaap_RelatedPartyDomain_01a01532-f249-70be-b87f-df2046b06ad2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyMember_01a01532-f249-777f-969f-3fe7f4f5dfdf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_01a01532-f249-70be-b87f-df2046b06ad2" xlink:to="loc_us-gaap_RelatedPartyMember_01a01532-f249-777f-969f-3fe7f4f5dfdf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseDebt_019f660f-6aa0-70cd-a52f-7b6699f4ceef" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestExpenseDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtLineItems_019f660f-6aa0-75b5-a29b-af3ad7085afb" xlink:to="loc_us-gaap_InterestExpenseDebt_019f660f-6aa0-70cd-a52f-7b6699f4ceef" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtConversionOriginalDebtAmount1_019f660f-6aa0-730b-b186-e9d929c8538e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtConversionOriginalDebtAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtLineItems_019f660f-6aa0-75b5-a29b-af3ad7085afb" xlink:to="loc_us-gaap_DebtConversionOriginalDebtAmount1_019f660f-6aa0-730b-b186-e9d929c8538e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued_01a000e8-5d49-72dc-8662-7e6c763c8aa8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtLineItems_019f660f-6aa0-75b5-a29b-af3ad7085afb" xlink:to="loc_us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued_01a000e8-5d49-72dc-8662-7e6c763c8aa8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityOwnershipPercentageExcludingConsolidatedEntityAndEquityMethodInvestee_01a000e8-5d49-71a6-9f27-4da3cbc0df56" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityOwnershipPercentageExcludingConsolidatedEntityAndEquityMethodInvestee"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtLineItems_019f660f-6aa0-75b5-a29b-af3ad7085afb" xlink:to="loc_us-gaap_EquityOwnershipPercentageExcludingConsolidatedEntityAndEquityMethodInvestee_01a000e8-5d49-71a6-9f27-4da3cbc0df56" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtPercentageBearingVariableInterestRate_019f660f-6aa0-7eb1-83a5-657b6d649ba7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortTermDebtPercentageBearingVariableInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtLineItems_019f660f-6aa0-75b5-a29b-af3ad7085afb" xlink:to="loc_us-gaap_ShortTermDebtPercentageBearingVariableInterestRate_019f660f-6aa0-7eb1-83a5-657b6d649ba7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTerm_019f660f-6aa0-7864-9912-46c213dcc449" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtLineItems_019f660f-6aa0-75b5-a29b-af3ad7085afb" xlink:to="loc_us-gaap_DebtInstrumentTerm_019f660f-6aa0-7864-9912-46c213dcc449" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRepaidPrincipal_019f855e-9bd1-7ea8-be46-1e60e34385d9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentRepaidPrincipal"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtLineItems_019f660f-6aa0-75b5-a29b-af3ad7085afb" xlink:to="loc_us-gaap_DebtInstrumentRepaidPrincipal_019f855e-9bd1-7ea8-be46-1e60e34385d9" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfDebt_019f660f-6aa0-7da2-8a78-8c96170bd97c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RepaymentsOfDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtLineItems_019f660f-6aa0-75b5-a29b-af3ad7085afb" xlink:to="loc_us-gaap_RepaymentsOfDebt_019f660f-6aa0-7da2-8a78-8c96170bd97c" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtNoncurrent_019fcdb0-acdc-7815-a2c2-b166eb9b294e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermDebtNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtLineItems_019f660f-6aa0-75b5-a29b-af3ad7085afb" xlink:to="loc_us-gaap_LongTermDebtNoncurrent_019fcdb0-acdc-7815-a2c2-b166eb9b294e" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_LongTermLineOfCreditBorrowingBase_019fcdec-1456-7f65-91f2-f9a9c1094a28" xlink:href="xtia-20260630.xsd#xtia_LongTermLineOfCreditBorrowingBase"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtLineItems_019f660f-6aa0-75b5-a29b-af3ad7085afb" xlink:to="loc_xtia_LongTermLineOfCreditBorrowingBase_019fcdec-1456-7f65-91f2-f9a9c1094a28" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_019f660f-6aa0-7a5f-9344-f9e5c22fdcd8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtLineItems_019f660f-6aa0-75b5-a29b-af3ad7085afb" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_019f660f-6aa0-7a5f-9344-f9e5c22fdcd8" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCredit_019fcdb2-455a-7c03-9d85-9683bb3917c2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtLineItems_019f660f-6aa0-75b5-a29b-af3ad7085afb" xlink:to="loc_us-gaap_LineOfCredit_019fcdb2-455a-7c03-9d85-9683bb3917c2" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_019f660f-6aa0-7427-8ea1-cbfcb35d2708" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtLineItems_019f660f-6aa0-75b5-a29b-af3ad7085afb" xlink:to="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_019f660f-6aa0-7427-8ea1-cbfcb35d2708" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityCommitmentFeePercentage_019f8564-1daf-747b-aec8-e06e992d3246" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditFacilityCommitmentFeePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtLineItems_019f660f-6aa0-75b5-a29b-af3ad7085afb" xlink:to="loc_us-gaap_LineOfCreditFacilityCommitmentFeePercentage_019f8564-1daf-747b-aec8-e06e992d3246" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtWeightedAverageInterestRate_019f660f-6aa0-792c-9355-1315e7c8fb43" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtWeightedAverageInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtLineItems_019f660f-6aa0-75b5-a29b-af3ad7085afb" xlink:to="loc_us-gaap_DebtWeightedAverageInterestRate_019f660f-6aa0-792c-9355-1315e7c8fb43" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_MinimumFixedChargeCoverageRatio_01a1317d-d995-7ef6-a330-e3f7e1e36d3b" xlink:href="xtia-20260630.xsd#xtia_MinimumFixedChargeCoverageRatio"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtLineItems_019f660f-6aa0-75b5-a29b-af3ad7085afb" xlink:to="loc_xtia_MinimumFixedChargeCoverageRatio_01a1317d-d995-7ef6-a330-e3f7e1e36d3b" xlink:type="arc" order="15"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.xtiaircraft.com/role/CapitalStructureNarrativeDetails" xlink:type="simple" xlink:href="xtia-20260630.xsd#CapitalStructureNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.xtiaircraft.com/role/CapitalStructureNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockLineItems_019f660f-6aa0-7b1d-8487-413ddba2efc1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_CapitalStructureDetailsTable_019f660f-6aa0-7c8a-bcda-3663833aeb9b" xlink:href="xtia-20260630.xsd#xtia_CapitalStructureDetailsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ClassOfStockLineItems_019f660f-6aa0-7b1d-8487-413ddba2efc1" xlink:to="loc_xtia_CapitalStructureDetailsTable_019f660f-6aa0-7c8a-bcda-3663833aeb9b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_019f660f-6aa0-7072-9358-65061125093d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_xtia_CapitalStructureDetailsTable_019f660f-6aa0-7c8a-bcda-3663833aeb9b" xlink:to="loc_us-gaap_StatementClassOfStockAxis_019f660f-6aa0-7072-9358-65061125093d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_019f660f-6aa0-7072-9358-65061125093d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_019f660f-6aa0-7072-9358-65061125093d" xlink:to="loc_us-gaap_ClassOfStockDomain_019f660f-6aa0-7072-9358-65061125093d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_019f660f-6aa0-7420-9537-f9ddb7b1a7b5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_019f660f-6aa0-7072-9358-65061125093d" xlink:to="loc_us-gaap_ClassOfStockDomain_019f660f-6aa0-7420-9537-f9ddb7b1a7b5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_Series10ConvertiblePreferredStockMember_019f660f-6aa0-783c-917c-f65044718789" xlink:href="xtia-20260630.xsd#xtia_Series10ConvertiblePreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019f660f-6aa0-7420-9537-f9ddb7b1a7b5" xlink:to="loc_xtia_Series10ConvertiblePreferredStockMember_019f660f-6aa0-783c-917c-f65044718789" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_Series9ConvertiblePreferredStockMember_01a01fa3-6e5a-7e8c-b495-960f26be110a" xlink:href="xtia-20260630.xsd#xtia_Series9ConvertiblePreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019f660f-6aa0-7420-9537-f9ddb7b1a7b5" xlink:to="loc_xtia_Series9ConvertiblePreferredStockMember_01a01fa3-6e5a-7e8c-b495-960f26be110a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_NoncontrollingInterestClassBUnitsMember_019f660f-6aa0-77bf-9f1f-a47ee04a7aa2" xlink:href="xtia-20260630.xsd#xtia_NoncontrollingInterestClassBUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019f660f-6aa0-7420-9537-f9ddb7b1a7b5" xlink:to="loc_xtia_NoncontrollingInterestClassBUnitsMember_019f660f-6aa0-77bf-9f1f-a47ee04a7aa2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_ClassBUnitsMember_019f660f-6aa0-77ce-b2eb-778c9613447a" xlink:href="xtia-20260630.xsd#xtia_ClassBUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019f660f-6aa0-7420-9537-f9ddb7b1a7b5" xlink:to="loc_xtia_ClassBUnitsMember_019f660f-6aa0-77ce-b2eb-778c9613447a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_ClassAUnitsMember_019f660f-6aa0-7c82-bfd9-2091cfb7c4cc" xlink:href="xtia-20260630.xsd#xtia_ClassAUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019f660f-6aa0-7420-9537-f9ddb7b1a7b5" xlink:to="loc_xtia_ClassAUnitsMember_019f660f-6aa0-7c82-bfd9-2091cfb7c4cc" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsidiarySaleOfStockAxis_019f660f-6aa0-720d-a704-440279e9cb41" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsidiarySaleOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_xtia_CapitalStructureDetailsTable_019f660f-6aa0-7c8a-bcda-3663833aeb9b" xlink:to="loc_us-gaap_SubsidiarySaleOfStockAxis_019f660f-6aa0-720d-a704-440279e9cb41" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_019f660f-6aa0-720d-a704-440279e9cb41_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_019f660f-6aa0-720d-a704-440279e9cb41" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_019f660f-6aa0-720d-a704-440279e9cb41_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_019f660f-6aa0-7895-a5c4-d37c80baf814" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_019f660f-6aa0-720d-a704-440279e9cb41" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_019f660f-6aa0-7895-a5c4-d37c80baf814" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_PublicOfferingMember_019f660f-6aa0-7803-8064-8a0637808fdd" xlink:href="xtia-20260630.xsd#xtia_PublicOfferingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SaleOfStockNameOfTransactionDomain_019f660f-6aa0-7895-a5c4-d37c80baf814" xlink:to="loc_xtia_PublicOfferingMember_019f660f-6aa0-7803-8064-8a0637808fdd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_019f660f-6aa0-7111-86da-18cc0fcafe23" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_xtia_CapitalStructureDetailsTable_019f660f-6aa0-7c8a-bcda-3663833aeb9b" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_019f660f-6aa0-7111-86da-18cc0fcafe23" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019f660f-6aa0-7111-86da-18cc0fcafe23_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019f660f-6aa0-7111-86da-18cc0fcafe23" xlink:to="loc_us-gaap_EquityComponentDomain_019f660f-6aa0-7111-86da-18cc0fcafe23_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019f660f-6aa0-796b-a3fc-418900a1e28b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019f660f-6aa0-7111-86da-18cc0fcafe23" xlink:to="loc_us-gaap_EquityComponentDomain_019f660f-6aa0-796b-a3fc-418900a1e28b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_019f660f-6aa0-7c80-b373-0a597a856214" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019f660f-6aa0-796b-a3fc-418900a1e28b" xlink:to="loc_us-gaap_CommonStockMember_019f660f-6aa0-7c80-b373-0a597a856214" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightAxis_019f660f-6aa0-746e-8e8d-b1b1f7db350e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_xtia_CapitalStructureDetailsTable_019f660f-6aa0-7c8a-bcda-3663833aeb9b" xlink:to="loc_us-gaap_ClassOfWarrantOrRightAxis_019f660f-6aa0-746e-8e8d-b1b1f7db350e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightDomain_019f660f-6aa0-746e-8e8d-b1b1f7db350e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ClassOfWarrantOrRightAxis_019f660f-6aa0-746e-8e8d-b1b1f7db350e" xlink:to="loc_us-gaap_ClassOfWarrantOrRightDomain_019f660f-6aa0-746e-8e8d-b1b1f7db350e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightDomain_019f660f-6aa0-7a02-b929-a673dc43c2d3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ClassOfWarrantOrRightAxis_019f660f-6aa0-746e-8e8d-b1b1f7db350e" xlink:to="loc_us-gaap_ClassOfWarrantOrRightDomain_019f660f-6aa0-7a02-b929-a673dc43c2d3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_PreFundedWarrantsMember_019f660f-6aa0-7eb6-bc14-11557b5dfb6e" xlink:href="xtia-20260630.xsd#xtia_PreFundedWarrantsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightDomain_019f660f-6aa0-7a02-b929-a673dc43c2d3" xlink:to="loc_xtia_PreFundedWarrantsMember_019f660f-6aa0-7eb6-bc14-11557b5dfb6e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WarrantMember_019f660f-6aa0-71bd-a470-edebeca16725" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WarrantMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightDomain_019f660f-6aa0-7a02-b929-a673dc43c2d3" xlink:to="loc_us-gaap_WarrantMember_019f660f-6aa0-71bd-a470-edebeca16725" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_LiabilityClassifiedWarrantsMember_019f660f-6aa0-7472-ba1c-bcaae9a6cfe8" xlink:href="xtia-20260630.xsd#xtia_LiabilityClassifiedWarrantsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightDomain_019f660f-6aa0-7a02-b929-a673dc43c2d3" xlink:to="loc_xtia_LiabilityClassifiedWarrantsMember_019f660f-6aa0-7472-ba1c-bcaae9a6cfe8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_019f660f-6aa0-7606-a868-3bd9d5d86ec8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_xtia_CapitalStructureDetailsTable_019f660f-6aa0-7c8a-bcda-3663833aeb9b" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_019f660f-6aa0-7606-a868-3bd9d5d86ec8" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f660f-6aa0-7606-a868-3bd9d5d86ec8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019f660f-6aa0-7606-a868-3bd9d5d86ec8" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f660f-6aa0-7606-a868-3bd9d5d86ec8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f660f-6aa0-7de9-a83f-d09b30c7fb3d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019f660f-6aa0-7606-a868-3bd9d5d86ec8" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f660f-6aa0-7de9-a83f-d09b30c7fb3d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_XTIDroneHoldingsMember_019f660f-6aa0-7d7a-8a10-059d1c348618" xlink:href="xtia-20260630.xsd#xtia_XTIDroneHoldingsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019f660f-6aa0-7de9-a83f-d09b30c7fb3d" xlink:to="loc_xtia_XTIDroneHoldingsMember_019f660f-6aa0-7d7a-8a10-059d1c348618" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_01a01533-37cf-7250-8e7d-b63038707d58" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_xtia_CapitalStructureDetailsTable_019f660f-6aa0-7c8a-bcda-3663833aeb9b" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_01a01533-37cf-7250-8e7d-b63038707d58" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_01a01533-37cf-7250-8e7d-b63038707d58_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_01a01533-37cf-7250-8e7d-b63038707d58" xlink:to="loc_us-gaap_RelatedPartyDomain_01a01533-37cf-7250-8e7d-b63038707d58_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_01a01533-37cf-7b10-95e4-d37569399dfe" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_01a01533-37cf-7250-8e7d-b63038707d58" xlink:to="loc_us-gaap_RelatedPartyDomain_01a01533-37cf-7b10-95e4-d37569399dfe" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyMember_01a01533-37cf-7987-a30f-ba8db17443b4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_01a01533-37cf-7b10-95e4-d37569399dfe" xlink:to="loc_us-gaap_RelatedPartyMember_01a01533-37cf-7987-a30f-ba8db17443b4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesAuthorized_019f660f-6aa0-7ebb-8e08-2b63b0b3761c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_019f660f-6aa0-7b1d-8487-413ddba2efc1" xlink:to="loc_us-gaap_CommonStockSharesAuthorized_019f660f-6aa0-7ebb-8e08-2b63b0b3761c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockParOrStatedValuePerShare_019f660f-6aa0-760b-ab67-635d49af9a5b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockParOrStatedValuePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_019f660f-6aa0-7b1d-8487-413ddba2efc1" xlink:to="loc_us-gaap_CommonStockParOrStatedValuePerShare_019f660f-6aa0-760b-ab67-635d49af9a5b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesAuthorized_019f660f-6aa0-72da-8009-cb7a1d375380" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_019f660f-6aa0-7b1d-8487-413ddba2efc1" xlink:to="loc_us-gaap_PreferredStockSharesAuthorized_019f660f-6aa0-72da-8009-cb7a1d375380" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockParOrStatedValuePerShare_019f660f-6aa0-78c2-9689-461d46353671" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockParOrStatedValuePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_019f660f-6aa0-7b1d-8487-413ddba2efc1" xlink:to="loc_us-gaap_PreferredStockParOrStatedValuePerShare_019f660f-6aa0-78c2-9689-461d46353671" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityNoteStockSplitConversionRatio1_01a01f9f-2c24-7c8f-b497-aa12d289ddbf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquityNoteStockSplitConversionRatio1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_019f660f-6aa0-7b1d-8487-413ddba2efc1" xlink:to="loc_us-gaap_StockholdersEquityNoteStockSplitConversionRatio1_01a01f9f-2c24-7c8f-b497-aa12d289ddbf" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockConvertibleConversionPrice_019f660f-6aa0-7110-ab56-86660d1cc0c3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockConvertibleConversionPrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_019f660f-6aa0-7b1d-8487-413ddba2efc1" xlink:to="loc_us-gaap_PreferredStockConvertibleConversionPrice_019f660f-6aa0-7110-ab56-86660d1cc0c3" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesIssued_019f660f-6aa0-79d8-a385-a91a41f9d9a3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_019f660f-6aa0-7b1d-8487-413ddba2efc1" xlink:to="loc_us-gaap_CommonStockSharesIssued_019f660f-6aa0-79d8-a385-a91a41f9d9a3" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_019f660f-6aa0-7133-8ada-b3afa3c1dcda" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_019f660f-6aa0-7b1d-8487-413ddba2efc1" xlink:to="loc_us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_019f660f-6aa0-7133-8ada-b3afa3c1dcda" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightOutstanding_019f660f-6aa0-799a-b924-8f2a6e72ba7b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_019f660f-6aa0-7b1d-8487-413ddba2efc1" xlink:to="loc_us-gaap_ClassOfWarrantOrRightOutstanding_019f660f-6aa0-799a-b924-8f2a6e72ba7b" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_019f660f-6aa0-7c10-934e-6c1548e6b226" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromIssuanceOfCommonStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_019f660f-6aa0-7b1d-8487-413ddba2efc1" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfCommonStock_019f660f-6aa0-7c10-934e-6c1548e6b226" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalCommonStock_019f660f-6aa0-7780-8eaa-993e9e6caf92" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdditionalPaidInCapitalCommonStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_019f660f-6aa0-7b1d-8487-413ddba2efc1" xlink:to="loc_us-gaap_AdditionalPaidInCapitalCommonStock_019f660f-6aa0-7780-8eaa-993e9e6caf92" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConversionOfStockSharesConverted1_01a01fa5-9114-7387-8eb7-e640cf5f3847" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConversionOfStockSharesConverted1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_019f660f-6aa0-7b1d-8487-413ddba2efc1" xlink:to="loc_us-gaap_ConversionOfStockSharesConverted1_01a01fa5-9114-7387-8eb7-e640cf5f3847" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConvertiblePreferredStockSharesIssuedUponConversion_01a01fa4-9824-7e54-96da-a95cfe294bb2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConvertiblePreferredStockSharesIssuedUponConversion"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_019f660f-6aa0-7b1d-8487-413ddba2efc1" xlink:to="loc_us-gaap_ConvertiblePreferredStockSharesIssuedUponConversion_01a01fa4-9824-7e54-96da-a95cfe294bb2" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConversionOfStockAmountConverted1_01a01faa-5084-7890-8765-0f9be86d3a2e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConversionOfStockAmountConverted1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_019f660f-6aa0-7b1d-8487-413ddba2efc1" xlink:to="loc_us-gaap_ConversionOfStockAmountConverted1_01a01faa-5084-7890-8765-0f9be86d3a2e" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesOutstanding_01a01faf-8752-7496-8974-556ab135d387" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_019f660f-6aa0-7b1d-8487-413ddba2efc1" xlink:to="loc_us-gaap_PreferredStockSharesOutstanding_01a01faf-8752-7496-8974-556ab135d387" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfStockIssuanceCosts_019fcdb5-bfdb-70c6-9bff-7fcea85e04ea" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsOfStockIssuanceCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_019f660f-6aa0-7b1d-8487-413ddba2efc1" xlink:to="loc_us-gaap_PaymentsOfStockIssuanceCosts_019fcdb5-bfdb-70c6-9bff-7fcea85e04ea" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfWarrants_019f660f-6aa0-7165-a5b4-2f332de1811f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromIssuanceOfWarrants"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_019f660f-6aa0-7b1d-8487-413ddba2efc1" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfWarrants_019f660f-6aa0-7165-a5b4-2f332de1811f" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued_019f660f-6aa0-71a2-91fe-2fd00c013fc1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_019f660f-6aa0-7b1d-8487-413ddba2efc1" xlink:to="loc_us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued_019f660f-6aa0-71a2-91fe-2fd00c013fc1" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityOwnershipPercentageExcludingConsolidatedEntityAndEquityMethodInvestee_019f660f-6aa0-7fc8-a36c-db9b29ba38ef" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityOwnershipPercentageExcludingConsolidatedEntityAndEquityMethodInvestee"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_019f660f-6aa0-7b1d-8487-413ddba2efc1" xlink:to="loc_us-gaap_EquityOwnershipPercentageExcludingConsolidatedEntityAndEquityMethodInvestee_019f660f-6aa0-7fc8-a36c-db9b29ba38ef" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_ConversionOfStockSharesConversionBasisPerEachShare_019fcdb7-ea7c-7854-99d9-54b340af5ce6" xlink:href="xtia-20260630.xsd#xtia_ConversionOfStockSharesConversionBasisPerEachShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_019f660f-6aa0-7b1d-8487-413ddba2efc1" xlink:to="loc_xtia_ConversionOfStockSharesConversionBasisPerEachShare_019fcdb7-ea7c-7854-99d9-54b340af5ce6" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_ConversionOfStockAutomaticExchangePeriod_01a154c3-b0f8-74cf-a4a3-c6b1afa860e0" xlink:href="xtia-20260630.xsd#xtia_ConversionOfStockAutomaticExchangePeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_019f660f-6aa0-7b1d-8487-413ddba2efc1" xlink:to="loc_xtia_ConversionOfStockAutomaticExchangePeriod_01a154c3-b0f8-74cf-a4a3-c6b1afa860e0" xlink:type="arc" order="20"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.xtiaircraft.com/role/CapitalStructureScheduleofWarrantsOutstandingDetails" xlink:type="simple" xlink:href="xtia-20260630.xsd#CapitalStructureScheduleofWarrantsOutstandingDetails"/>
  <link:definitionLink xlink:role="http://www.xtiaircraft.com/role/CapitalStructureScheduleofWarrantsOutstandingDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightLineItems_019f660f-6aa0-71b7-80ff-4b91ec7659f2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightTable_019f660f-6aa0-723c-9ac0-bcf87cf4bda3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ClassOfWarrantOrRightLineItems_019f660f-6aa0-71b7-80ff-4b91ec7659f2" xlink:to="loc_us-gaap_ClassOfWarrantOrRightTable_019f660f-6aa0-723c-9ac0-bcf87cf4bda3" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightAxis_019f660f-6aa0-71f2-9ef9-e637edd62609" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ClassOfWarrantOrRightTable_019f660f-6aa0-723c-9ac0-bcf87cf4bda3" xlink:to="loc_us-gaap_ClassOfWarrantOrRightAxis_019f660f-6aa0-71f2-9ef9-e637edd62609" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightDomain_019f660f-6aa0-71f2-9ef9-e637edd62609_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ClassOfWarrantOrRightAxis_019f660f-6aa0-71f2-9ef9-e637edd62609" xlink:to="loc_us-gaap_ClassOfWarrantOrRightDomain_019f660f-6aa0-71f2-9ef9-e637edd62609_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightDomain_019f660f-6aa0-7f93-9895-320ffbc98049" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ClassOfWarrantOrRightAxis_019f660f-6aa0-71f2-9ef9-e637edd62609" xlink:to="loc_us-gaap_ClassOfWarrantOrRightDomain_019f660f-6aa0-7f93-9895-320ffbc98049" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WarrantMember_019f660f-6aa0-7fb4-a357-161381e12035" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WarrantMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightDomain_019f660f-6aa0-7f93-9895-320ffbc98049" xlink:to="loc_us-gaap_WarrantMember_019f660f-6aa0-7fb4-a357-161381e12035" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward_019f8580-b185-7f34-948a-faf079fa1b9d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightLineItems_019f660f-6aa0-71b7-80ff-4b91ec7659f2" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward_019f8580-b185-7f34-948a-faf079fa1b9d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber_019f660f-6aa0-7ff5-b3e3-a4bf581d8724" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward_019f8580-b185-7f34-948a-faf079fa1b9d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber_019f660f-6aa0-7ff5-b3e3-a4bf581d8724" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsLegacyInpixonWarrants_019f660f-6aa0-729a-96b4-221b24c27eb6" xlink:href="xtia-20260630.xsd#xtia_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsLegacyInpixonWarrants"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward_019f8580-b185-7f34-948a-faf079fa1b9d" xlink:to="loc_xtia_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsLegacyInpixonWarrants_019f660f-6aa0-729a-96b4-221b24c27eb6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercised_019f660f-6aa0-746d-9fdb-fd7db74f92cd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward_019f8580-b185-7f34-948a-faf079fa1b9d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercised_019f660f-6aa0-746d-9fdb-fd7db74f92cd" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber_019f660f-6aa0-76fb-89ac-2568e9522c46" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollforwardRollForward_019fcdd0-e5f0-72f5-b71f-153024b630ea" xlink:href="xtia-20260630.xsd#xtia_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollforwardRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightLineItems_019f660f-6aa0-71b7-80ff-4b91ec7659f2" xlink:to="loc_xtia_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollforwardRollForward_019fcdd0-e5f0-72f5-b71f-153024b630ea" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingWeightedAverageExercisePrice_019f660f-6aa0-75df-aa90-720504aa30e4" xlink:href="xtia-20260630.xsd#xtia_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_xtia_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollforwardRollForward_019fcdd0-e5f0-72f5-b71f-153024b630ea" xlink:to="loc_xtia_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingWeightedAverageExercisePrice_019f660f-6aa0-75df-aa90-720504aa30e4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingLegacyInpixonWarrants_019f660f-6aa0-7502-8f94-a6fa963fb293" xlink:href="xtia-20260630.xsd#xtia_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingLegacyInpixonWarrants"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_xtia_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollforwardRollForward_019fcdd0-e5f0-72f5-b71f-153024b630ea" xlink:to="loc_xtia_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingLegacyInpixonWarrants_019f660f-6aa0-7502-8f94-a6fa963fb293" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercisedWeightedAverageExercisePrice_019f660f-6aa0-74d2-a4e9-ab48cf00c381" xlink:href="xtia-20260630.xsd#xtia_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercisedWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_xtia_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollforwardRollForward_019fcdd0-e5f0-72f5-b71f-153024b630ea" xlink:to="loc_xtia_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercisedWeightedAverageExercisePrice_019f660f-6aa0-74d2-a4e9-ab48cf00c381" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingWeightedAverageExercisePrice_019f660f-6aa0-78b6-9da7-f8ed4bdedd0d" xlink:href="xtia-20260630.xsd#xtia_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingWeightedAverageExercisePrice"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercisable_019f660f-6aa0-74cb-986d-85eeb926a4ae" xlink:href="xtia-20260630.xsd#xtia_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercisable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightLineItems_019f660f-6aa0-71b7-80ff-4b91ec7659f2" xlink:to="loc_xtia_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercisable_019f660f-6aa0-74cb-986d-85eeb926a4ae" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercisableWeightedAverageExercisePrice_019f660f-6aa0-7367-bb0b-e3a09924939e" xlink:href="xtia-20260630.xsd#xtia_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercisableWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightLineItems_019f660f-6aa0-71b7-80ff-4b91ec7659f2" xlink:to="loc_xtia_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercisableWeightedAverageExercisePrice_019f660f-6aa0-7367-bb0b-e3a09924939e" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.xtiaircraft.com/role/StockAwardPlansandStockBasedCompensationNarrativeDetails" xlink:type="simple" xlink:href="xtia-20260630.xsd#StockAwardPlansandStockBasedCompensationNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.xtiaircraft.com/role/StockAwardPlansandStockBasedCompensationNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_019f660f-6aa0-7942-b9d0-3d7d3e4bfe2b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_StockAwardPlansandStockBasedCompensationDetailsTable_019f660f-6aa0-71fe-9c79-361e6074cfef" xlink:href="xtia-20260630.xsd#xtia_StockAwardPlansandStockBasedCompensationDetailsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_019f660f-6aa0-7942-b9d0-3d7d3e4bfe2b" xlink:to="loc_xtia_StockAwardPlansandStockBasedCompensationDetailsTable_019f660f-6aa0-71fe-9c79-361e6074cfef" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019f660f-6aa0-7048-8e01-bd0378b7389f" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_xtia_StockAwardPlansandStockBasedCompensationDetailsTable_019f660f-6aa0-71fe-9c79-361e6074cfef" xlink:to="loc_srt_RangeAxis_019f660f-6aa0-7048-8e01-bd0378b7389f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019f660f-6aa0-7048-8e01-bd0378b7389f_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019f660f-6aa0-7048-8e01-bd0378b7389f" xlink:to="loc_srt_RangeMember_019f660f-6aa0-7048-8e01-bd0378b7389f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019f660f-6aa0-72d3-a01c-4d61359c108b" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019f660f-6aa0-7048-8e01-bd0378b7389f" xlink:to="loc_srt_RangeMember_019f660f-6aa0-72d3-a01c-4d61359c108b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019f660f-6aa0-7ea4-b7fb-032953778a6b" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019f660f-6aa0-72d3-a01c-4d61359c108b" xlink:to="loc_srt_MinimumMember_019f660f-6aa0-7ea4-b7fb-032953778a6b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019f660f-6aa0-7709-ab48-21bf6dec0224" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019f660f-6aa0-72d3-a01c-4d61359c108b" xlink:to="loc_srt_MaximumMember_019f660f-6aa0-7709-ab48-21bf6dec0224" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_019f660f-6aa0-70c5-95bb-2a17cda08727" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_xtia_StockAwardPlansandStockBasedCompensationDetailsTable_019f660f-6aa0-71fe-9c79-361e6074cfef" xlink:to="loc_us-gaap_PlanNameAxis_019f660f-6aa0-70c5-95bb-2a17cda08727" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_019f660f-6aa0-70c5-95bb-2a17cda08727_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_019f660f-6aa0-70c5-95bb-2a17cda08727" xlink:to="loc_us-gaap_PlanNameDomain_019f660f-6aa0-70c5-95bb-2a17cda08727_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_019f660f-6aa0-7b0a-9862-c6d1826f53ba" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_019f660f-6aa0-70c5-95bb-2a17cda08727" xlink:to="loc_us-gaap_PlanNameDomain_019f660f-6aa0-7b0a-9862-c6d1826f53ba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_TwoThousandEighteenPlanMember_019f660f-6aa0-7dbf-927d-9b6a7e35ee58" xlink:href="xtia-20260630.xsd#xtia_TwoThousandEighteenPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_019f660f-6aa0-7b0a-9862-c6d1826f53ba" xlink:to="loc_xtia_TwoThousandEighteenPlanMember_019f660f-6aa0-7dbf-927d-9b6a7e35ee58" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_019f660f-6aa0-758d-a9ef-2c99671482b7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_xtia_StockAwardPlansandStockBasedCompensationDetailsTable_019f660f-6aa0-71fe-9c79-361e6074cfef" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_019f660f-6aa0-758d-a9ef-2c99671482b7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019f660f-6aa0-758d-a9ef-2c99671482b7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019f660f-6aa0-758d-a9ef-2c99671482b7" xlink:to="loc_us-gaap_EquityComponentDomain_019f660f-6aa0-758d-a9ef-2c99671482b7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019f660f-6aa0-7949-b41b-508c26dda102" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019f660f-6aa0-758d-a9ef-2c99671482b7" xlink:to="loc_us-gaap_EquityComponentDomain_019f660f-6aa0-7949-b41b-508c26dda102" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_019f660f-6aa0-7c57-b505-5041fe143a2a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019f660f-6aa0-7949-b41b-508c26dda102" xlink:to="loc_us-gaap_CommonStockMember_019f660f-6aa0-7c57-b505-5041fe143a2a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_019f857b-9a40-7c68-a52d-dd32a998c7f8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_xtia_StockAwardPlansandStockBasedCompensationDetailsTable_019f660f-6aa0-71fe-9c79-361e6074cfef" xlink:to="loc_us-gaap_StatementClassOfStockAxis_019f857b-9a40-7c68-a52d-dd32a998c7f8" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_019f857b-9a40-7c68-a52d-dd32a998c7f8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_019f857b-9a40-7c68-a52d-dd32a998c7f8" xlink:to="loc_us-gaap_ClassOfStockDomain_019f857b-9a40-7c68-a52d-dd32a998c7f8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_019f857b-9a40-7c12-ac1c-e1051227bd3a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_019f857b-9a40-7c68-a52d-dd32a998c7f8" xlink:to="loc_us-gaap_ClassOfStockDomain_019f857b-9a40-7c12-ac1c-e1051227bd3a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockMember_019f857b-c6ea-7738-a39d-f19e91762288" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestrictedStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019f857b-9a40-7c12-ac1c-e1051227bd3a" xlink:to="loc_us-gaap_RestrictedStockMember_019f857b-c6ea-7738-a39d-f19e91762288" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_019f857c-2a15-7656-a224-5c9d832d2043" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_019f857b-9a40-7c12-ac1c-e1051227bd3a" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_019f857c-2a15-7656-a224-5c9d832d2043" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_019f660f-6aa0-72da-98a0-38af65db1e91" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_019f660f-6aa0-7942-b9d0-3d7d3e4bfe2b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_019f660f-6aa0-72da-98a0-38af65db1e91" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_019f660f-6aa0-75da-9844-34140d023224" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_019f660f-6aa0-7942-b9d0-3d7d3e4bfe2b" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_019f660f-6aa0-75da-9844-34140d023224" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_019f660f-6aa0-739f-90e6-33052bec5d6f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_019f660f-6aa0-7942-b9d0-3d7d3e4bfe2b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_019f660f-6aa0-739f-90e6-33052bec5d6f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod_019f660f-6aa0-7768-9e32-6e5f5092c08a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_019f660f-6aa0-7942-b9d0-3d7d3e4bfe2b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod_019f660f-6aa0-7768-9e32-6e5f5092c08a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantAndRegistered_019fcdef-6f00-7804-ada2-df3644357fbc" xlink:href="xtia-20260630.xsd#xtia_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantAndRegistered"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_019f660f-6aa0-7942-b9d0-3d7d3e4bfe2b" xlink:to="loc_xtia_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantAndRegistered_019fcdef-6f00-7804-ada2-df3644357fbc" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_019f660f-6aa0-7e3a-9981-d62e485e49a4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_019f660f-6aa0-7942-b9d0-3d7d3e4bfe2b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_019f660f-6aa0-7e3a-9981-d62e485e49a4" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_019f660f-6aa0-7da1-95f9-cf3472b8873f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_019f660f-6aa0-7942-b9d0-3d7d3e4bfe2b" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_019f660f-6aa0-7da1-95f9-cf3472b8873f" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_01a1560e-0c57-7900-82b8-b92818b938e9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_019f660f-6aa0-7942-b9d0-3d7d3e4bfe2b" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_01a1560e-0c57-7900-82b8-b92818b938e9" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_019f660f-6aa0-79cb-bb2b-77d64a7b8be2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_019f660f-6aa0-7942-b9d0-3d7d3e4bfe2b" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_019f660f-6aa0-79cb-bb2b-77d64a7b8be2" xlink:type="arc" order="8"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.xtiaircraft.com/role/StockAwardPlansandStockBasedCompensationScheduleofAssumptionsinEstimatingFairValuesofOptionsAwardedDetails" xlink:type="simple" xlink:href="xtia-20260630.xsd#StockAwardPlansandStockBasedCompensationScheduleofAssumptionsinEstimatingFairValuesofOptionsAwardedDetails"/>
  <link:definitionLink xlink:role="http://www.xtiaircraft.com/role/StockAwardPlansandStockBasedCompensationScheduleofAssumptionsinEstimatingFairValuesofOptionsAwardedDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f660f-6aa0-79de-b580-8c63bf129758" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019f660f-6aa0-7c92-be44-daf1473425c6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f660f-6aa0-79de-b580-8c63bf129758" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019f660f-6aa0-7c92-be44-daf1473425c6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019f660f-6aa0-79c4-b0cc-64aec090a44e" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019f660f-6aa0-7c92-be44-daf1473425c6" xlink:to="loc_srt_RangeAxis_019f660f-6aa0-79c4-b0cc-64aec090a44e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019f660f-6aa0-79c4-b0cc-64aec090a44e_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019f660f-6aa0-79c4-b0cc-64aec090a44e" xlink:to="loc_srt_RangeMember_019f660f-6aa0-79c4-b0cc-64aec090a44e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019f660f-6aa0-7375-9f32-d930563ef405" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019f660f-6aa0-79c4-b0cc-64aec090a44e" xlink:to="loc_srt_RangeMember_019f660f-6aa0-7375-9f32-d930563ef405" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019f660f-6aa0-7cf5-8caa-ad354d66b6dc" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019f660f-6aa0-7375-9f32-d930563ef405" xlink:to="loc_srt_MinimumMember_019f660f-6aa0-7cf5-8caa-ad354d66b6dc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019f660f-6aa0-7cf1-a3ed-b65dff857822" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019f660f-6aa0-7375-9f32-d930563ef405" xlink:to="loc_srt_MaximumMember_019f660f-6aa0-7cf1-a3ed-b65dff857822" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019f8587-f118-7ae5-aec6-3c5b72af09b7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019f660f-6aa0-7c92-be44-daf1473425c6" xlink:to="loc_us-gaap_AwardTypeAxis_019f8587-f118-7ae5-aec6-3c5b72af09b7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f8587-f118-7ae5-aec6-3c5b72af09b7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019f8587-f118-7ae5-aec6-3c5b72af09b7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f8587-f118-7ae5-aec6-3c5b72af09b7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f8587-f118-7899-85b0-704a5cb44d11" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019f8587-f118-7ae5-aec6-3c5b72af09b7" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f8587-f118-7899-85b0-704a5cb44d11" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_019f8588-21f5-7f16-a6fe-2e72eae24d7a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019f8587-f118-7899-85b0-704a5cb44d11" xlink:to="loc_us-gaap_EmployeeStockOptionMember_019f8588-21f5-7f16-a6fe-2e72eae24d7a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharePrice_019f660f-6aa0-7963-a5b7-039fe267569f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f660f-6aa0-79de-b580-8c63bf129758" xlink:to="loc_us-gaap_SharePrice_019f660f-6aa0-7963-a5b7-039fe267569f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExercisePrice_019f660f-6aa0-7133-bc30-c1c681875031" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f660f-6aa0-79de-b580-8c63bf129758" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExercisePrice_019f660f-6aa0-7133-bc30-c1c681875031" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_019f660f-6aa0-771a-bfc3-9e568137169f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f660f-6aa0-79de-b580-8c63bf129758" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_019f660f-6aa0-771a-bfc3-9e568137169f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum_019f8588-ead3-7d8e-9299-274d883c4d5e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f660f-6aa0-79de-b580-8c63bf129758" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum_019f8588-ead3-7d8e-9299-274d883c4d5e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum_019f660f-6aa0-7afd-b930-b37b30b7a6a8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f660f-6aa0-79de-b580-8c63bf129758" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum_019f660f-6aa0-7afd-b930-b37b30b7a6a8" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum_019f8589-1ae3-7bff-a163-8cfde4390009" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f660f-6aa0-79de-b580-8c63bf129758" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum_019f8589-1ae3-7bff-a163-8cfde4390009" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum_019f660f-6aa0-7621-9027-9db5592d55a6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f660f-6aa0-79de-b580-8c63bf129758" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum_019f660f-6aa0-7621-9027-9db5592d55a6" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_019f660f-6aa0-7bda-bf05-4d3435a60751" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019f660f-6aa0-79de-b580-8c63bf129758" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_019f660f-6aa0-7bda-bf05-4d3435a60751" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.xtiaircraft.com/role/StockAwardPlansandStockBasedCompensationScheduleofStockBasedCompensationChargesDetails" xlink:type="simple" xlink:href="xtia-20260630.xsd#StockAwardPlansandStockBasedCompensationScheduleofStockBasedCompensationChargesDetails"/>
  <link:definitionLink xlink:role="http://www.xtiaircraft.com/role/StockAwardPlansandStockBasedCompensationScheduleofStockBasedCompensationChargesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_019f660f-6aa0-765f-b968-75086f4a575a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_019f660f-6aa0-7db7-a418-db621f3eef08" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_019f660f-6aa0-765f-b968-75086f4a575a" xlink:to="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_019f660f-6aa0-7db7-a418-db621f3eef08" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_01a15ab5-afa6-7ef9-b3ac-b66114d2062d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementOfIncomeLocationBalanceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_019f660f-6aa0-7db7-a418-db621f3eef08" xlink:to="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_01a15ab5-afa6-7ef9-b3ac-b66114d2062d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_019f660f-6aa0-73a6-b764-bc09c0a11f71" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_019f660f-6aa0-765f-b968-75086f4a575a" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_019f660f-6aa0-73a6-b764-bc09c0a11f71" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.xtiaircraft.com/role/StockAwardPlansandStockBasedCompensationScheduleofStockBasedCompensationChargesDetails_1" xlink:type="simple" xlink:href="xtia-20260630.xsd#StockAwardPlansandStockBasedCompensationScheduleofStockBasedCompensationChargesDetails_1"/>
  <link:definitionLink xlink:role="http://www.xtiaircraft.com/role/StockAwardPlansandStockBasedCompensationScheduleofStockBasedCompensationChargesDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_019f660f-6aa0-765f-b968-75086f4a575a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_019f660f-6aa0-7db7-a418-db621f3eef08" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_019f660f-6aa0-765f-b968-75086f4a575a" xlink:to="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_019f660f-6aa0-7db7-a418-db621f3eef08" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_019f660f-6aa0-73a6-b764-bc09c0a11f71" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_019f660f-6aa0-765f-b968-75086f4a575a" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_019f660f-6aa0-73a6-b764-bc09c0a11f71" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.xtiaircraft.com/role/SegmentsScheduleofOperationsfromourBusinessSegmentsDetails" xlink:type="simple" xlink:href="xtia-20260630.xsd#SegmentsScheduleofOperationsfromourBusinessSegmentsDetails"/>
  <link:definitionLink xlink:role="http://www.xtiaircraft.com/role/SegmentsScheduleofOperationsfromourBusinessSegmentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_019f660f-6aa0-70ec-af0e-1d9a94d4fcfd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019f660f-6aa0-73c9-b31a-16dfafba3634" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f660f-6aa0-70ec-af0e-1d9a94d4fcfd" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019f660f-6aa0-73c9-b31a-16dfafba3634" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_019f660f-6aa0-77cf-bb7d-a30513a81d5a" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019f660f-6aa0-73c9-b31a-16dfafba3634" xlink:to="loc_srt_ConsolidationItemsAxis_019f660f-6aa0-77cf-bb7d-a30513a81d5a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019f660f-6aa0-77cf-bb7d-a30513a81d5a_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_019f660f-6aa0-77cf-bb7d-a30513a81d5a" xlink:to="loc_srt_ConsolidationItemsDomain_019f660f-6aa0-77cf-bb7d-a30513a81d5a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019f660f-6aa0-710a-bd87-d4077c2ecd71" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_019f660f-6aa0-77cf-bb7d-a30513a81d5a" xlink:to="loc_srt_ConsolidationItemsDomain_019f660f-6aa0-710a-bd87-d4077c2ecd71" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_019f660f-6aa0-70e1-a67b-5769932cfe26" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_019f660f-6aa0-710a-bd87-d4077c2ecd71" xlink:to="loc_us-gaap_OperatingSegmentsMember_019f660f-6aa0-70e1-a67b-5769932cfe26" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateNonSegmentMember_019f8590-91e4-7d83-a6f6-777f50b2d7b5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CorporateNonSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_019f660f-6aa0-710a-bd87-d4077c2ecd71" xlink:to="loc_us-gaap_CorporateNonSegmentMember_019f8590-91e4-7d83-a6f6-777f50b2d7b5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019f660f-6aa0-7209-8b13-cc270691f8ef" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019f660f-6aa0-73c9-b31a-16dfafba3634" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019f660f-6aa0-7209-8b13-cc270691f8ef" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019f660f-6aa0-7209-8b13-cc270691f8ef_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019f660f-6aa0-7209-8b13-cc270691f8ef" xlink:to="loc_us-gaap_SegmentDomain_019f660f-6aa0-7209-8b13-cc270691f8ef_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019f660f-6aa0-793d-ab3c-799df247e3b7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019f660f-6aa0-7209-8b13-cc270691f8ef" xlink:to="loc_us-gaap_SegmentDomain_019f660f-6aa0-793d-ab3c-799df247e3b7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_UASMember_019f660f-6aa0-760e-8178-538718a4e510" xlink:href="xtia-20260630.xsd#xtia_UASMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019f660f-6aa0-793d-ab3c-799df247e3b7" xlink:to="loc_xtia_UASMember_019f660f-6aa0-760e-8178-538718a4e510" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_ADSMember_019f660f-6aa0-7ff8-80ef-d5011075541a" xlink:href="xtia-20260630.xsd#xtia_ADSMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019f660f-6aa0-793d-ab3c-799df247e3b7" xlink:to="loc_xtia_ADSMember_019f660f-6aa0-7ff8-80ef-d5011075541a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_CommercialAviationMember_019f660f-6aa0-72b2-b496-1b3f5f61cf04" xlink:href="xtia-20260630.xsd#xtia_CommercialAviationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019f660f-6aa0-793d-ab3c-799df247e3b7" xlink:to="loc_xtia_CommercialAviationMember_019f660f-6aa0-72b2-b496-1b3f5f61cf04" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_01a0c9df-625d-761b-a13a-d6d5f2862cf3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementOfIncomeLocationBalanceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019f660f-6aa0-73c9-b31a-16dfafba3634" xlink:to="loc_us-gaap_StatementOfIncomeLocationBalanceAxis_01a0c9df-625d-761b-a13a-d6d5f2862cf3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementScenarioAxis_01a15adf-4cb7-717d-8da0-95431a0e3628" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_StatementScenarioAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019f660f-6aa0-73c9-b31a-16dfafba3634" xlink:to="loc_srt_StatementScenarioAxis_01a15adf-4cb7-717d-8da0-95431a0e3628" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_01a15adf-4cb7-717d-8da0-95431a0e3628_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementScenarioAxis_01a15adf-4cb7-717d-8da0-95431a0e3628" xlink:to="loc_srt_ScenarioUnspecifiedDomain_01a15adf-4cb7-717d-8da0-95431a0e3628_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_01a15adf-4cb7-7623-897e-753a7cdccef3" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementScenarioAxis_01a15adf-4cb7-717d-8da0-95431a0e3628" xlink:to="loc_srt_ScenarioUnspecifiedDomain_01a15adf-4cb7-7623-897e-753a7cdccef3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_ScenarioRoundingMember_01a15adf-859d-7f0c-9b0b-6a2275aa9515" xlink:href="xtia-20260630.xsd#xtia_ScenarioRoundingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ScenarioUnspecifiedDomain_01a15adf-4cb7-7623-897e-753a7cdccef3" xlink:to="loc_xtia_ScenarioRoundingMember_01a15adf-859d-7f0c-9b0b-6a2275aa9515" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_019f660f-6aa0-71af-87e5-3ea0dcd7352a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f660f-6aa0-70ec-af0e-1d9a94d4fcfd" xlink:to="loc_us-gaap_Revenues_019f660f-6aa0-71af-87e5-3ea0dcd7352a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfRevenue_019f660f-6aa0-74ff-b0cb-572f086aa68b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CostOfRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f660f-6aa0-70ec-af0e-1d9a94d4fcfd" xlink:to="loc_us-gaap_CostOfRevenue_019f660f-6aa0-74ff-b0cb-572f086aa68b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingExpensesAbstract_019f660f-6aa0-7dc5-8c2b-7ca46688cdeb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingExpensesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f660f-6aa0-70ec-af0e-1d9a94d4fcfd" xlink:to="loc_us-gaap_OperatingExpensesAbstract_019f660f-6aa0-7dc5-8c2b-7ca46688cdeb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_ResearchAndDevelopmentExpenseExcludingShareBasedCompensationExpense_01a0c9d4-8c4a-701e-b1ac-c0e762e9ab44" xlink:href="xtia-20260630.xsd#xtia_ResearchAndDevelopmentExpenseExcludingShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_019f660f-6aa0-7dc5-8c2b-7ca46688cdeb" xlink:to="loc_xtia_ResearchAndDevelopmentExpenseExcludingShareBasedCompensationExpense_01a0c9d4-8c4a-701e-b1ac-c0e762e9ab44" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_SellingAndMarketingExpenseExcludingShareBasedCompensationExpense_01a0c9d2-89ce-7b13-88ef-6b505fb90562" xlink:href="xtia-20260630.xsd#xtia_SellingAndMarketingExpenseExcludingShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_019f660f-6aa0-7dc5-8c2b-7ca46688cdeb" xlink:to="loc_xtia_SellingAndMarketingExpenseExcludingShareBasedCompensationExpense_01a0c9d2-89ce-7b13-88ef-6b505fb90562" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_GeneralAndAdministrativeExpenseExcludingShareBasedCompensationExpense_01a0c9d6-a4b3-7b52-a106-0dc5395b4c10" xlink:href="xtia-20260630.xsd#xtia_GeneralAndAdministrativeExpenseExcludingShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_019f660f-6aa0-7dc5-8c2b-7ca46688cdeb" xlink:to="loc_xtia_GeneralAndAdministrativeExpenseExcludingShareBasedCompensationExpense_01a0c9d6-a4b3-7b52-a106-0dc5395b4c10" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherGeneralExpense_019f660f-6aa0-74a3-9c16-0c37015e855f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherGeneralExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_019f660f-6aa0-7dc5-8c2b-7ca46688cdeb" xlink:to="loc_us-gaap_OtherGeneralExpense_019f660f-6aa0-74a3-9c16-0c37015e855f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingExpenses_019f660f-6aa0-7b2b-a4e8-82d260d2a4a0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_019f660f-6aa0-7dc5-8c2b-7ca46688cdeb" xlink:to="loc_us-gaap_OperatingExpenses_019f660f-6aa0-7b2b-a4e8-82d260d2a4a0" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_EarningsBeforeInterestTaxDepreciationAndAmortization_01a0c444-4aee-7b64-919b-b3c30d743882" xlink:href="xtia-20260630.xsd#xtia_EarningsBeforeInterestTaxDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f660f-6aa0-70ec-af0e-1d9a94d4fcfd" xlink:to="loc_xtia_EarningsBeforeInterestTaxDepreciationAndAmortization_01a0c444-4aee-7b64-919b-b3c30d743882" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_019f660f-6aa0-786b-991f-4f0b74fb9841" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f660f-6aa0-70ec-af0e-1d9a94d4fcfd" xlink:to="loc_us-gaap_OperatingIncomeLoss_019f660f-6aa0-786b-991f-4f0b74fb9841" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepreciationDepletionAndAmortization_01a0c444-faa0-739a-8a17-284329465458" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DepreciationDepletionAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f660f-6aa0-70ec-af0e-1d9a94d4fcfd" xlink:to="loc_us-gaap_DepreciationDepletionAndAmortization_01a0c444-faa0-739a-8a17-284329465458" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseNonoperating_01a0c9c2-08d7-758f-8947-1dad9733db96" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestExpenseNonoperating"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f660f-6aa0-70ec-af0e-1d9a94d4fcfd" xlink:to="loc_us-gaap_InterestExpenseNonoperating_01a0c9c2-08d7-758f-8947-1dad9733db96" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncashMergerRelatedCosts_01a0c9c2-08d7-7934-8247-647360fa66a9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NoncashMergerRelatedCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f660f-6aa0-70ec-af0e-1d9a94d4fcfd" xlink:to="loc_us-gaap_NoncashMergerRelatedCosts_01a0c9c2-08d7-7934-8247-647360fa66a9" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_01a0c9c0-6957-7152-9885-2dc16e216c77" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f660f-6aa0-70ec-af0e-1d9a94d4fcfd" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_01a0c9c0-6957-7152-9885-2dc16e216c77" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAdjustmentOfWarrants_01a0c9c2-08d7-7df1-84af-d964dcb0a028" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAdjustmentOfWarrants"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f660f-6aa0-70ec-af0e-1d9a94d4fcfd" xlink:to="loc_us-gaap_FairValueAdjustmentOfWarrants_01a0c9c2-08d7-7df1-84af-d964dcb0a028" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpense_01a0c9c2-08d7-7e00-b8c5-314968e9c8e6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherNonoperatingIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f660f-6aa0-70ec-af0e-1d9a94d4fcfd" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpense_01a0c9c2-08d7-7e00-b8c5-314968e9c8e6" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonoperatingIncomeExpense_01a01a68-dfa3-79a9-beba-7260a16896a5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NonoperatingIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f660f-6aa0-70ec-af0e-1d9a94d4fcfd" xlink:to="loc_us-gaap_NonoperatingIncomeExpense_01a01a68-dfa3-79a9-beba-7260a16896a5" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_01a000ea-d349-763d-955f-0e82c9769d02" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f660f-6aa0-70ec-af0e-1d9a94d4fcfd" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_01a000ea-d349-763d-955f-0e82c9769d02" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_01a000ea-d349-744f-b2a7-476ac41bab35" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f660f-6aa0-70ec-af0e-1d9a94d4fcfd" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_01a000ea-d349-744f-b2a7-476ac41bab35" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest_01a000ea-d349-75e8-b6d4-ab83434a9228" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f660f-6aa0-70ec-af0e-1d9a94d4fcfd" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest_01a000ea-d349-75e8-b6d4-ab83434a9228" xlink:type="arc" order="14"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.xtiaircraft.com/role/SegmentsScheduleofOperationsfromourBusinessSegmentsDetails_1" xlink:type="simple" xlink:href="xtia-20260630.xsd#SegmentsScheduleofOperationsfromourBusinessSegmentsDetails_1"/>
  <link:definitionLink xlink:role="http://www.xtiaircraft.com/role/SegmentsScheduleofOperationsfromourBusinessSegmentsDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_019f660f-6aa0-70ec-af0e-1d9a94d4fcfd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019f660f-6aa0-73c9-b31a-16dfafba3634" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f660f-6aa0-70ec-af0e-1d9a94d4fcfd" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019f660f-6aa0-73c9-b31a-16dfafba3634" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_019f660f-6aa0-77cf-bb7d-a30513a81d5a" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019f660f-6aa0-73c9-b31a-16dfafba3634" xlink:to="loc_srt_ConsolidationItemsAxis_019f660f-6aa0-77cf-bb7d-a30513a81d5a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019f660f-6aa0-77cf-bb7d-a30513a81d5a_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_019f660f-6aa0-77cf-bb7d-a30513a81d5a" xlink:to="loc_srt_ConsolidationItemsDomain_019f660f-6aa0-77cf-bb7d-a30513a81d5a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019f660f-6aa0-710a-bd87-d4077c2ecd71" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_019f660f-6aa0-77cf-bb7d-a30513a81d5a" xlink:to="loc_srt_ConsolidationItemsDomain_019f660f-6aa0-710a-bd87-d4077c2ecd71" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_019f660f-6aa0-70e1-a67b-5769932cfe26" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_019f660f-6aa0-710a-bd87-d4077c2ecd71" xlink:to="loc_us-gaap_OperatingSegmentsMember_019f660f-6aa0-70e1-a67b-5769932cfe26" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateNonSegmentMember_019f8590-91e4-7d83-a6f6-777f50b2d7b5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CorporateNonSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_019f660f-6aa0-710a-bd87-d4077c2ecd71" xlink:to="loc_us-gaap_CorporateNonSegmentMember_019f8590-91e4-7d83-a6f6-777f50b2d7b5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019f660f-6aa0-7209-8b13-cc270691f8ef" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019f660f-6aa0-73c9-b31a-16dfafba3634" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019f660f-6aa0-7209-8b13-cc270691f8ef" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019f660f-6aa0-7209-8b13-cc270691f8ef_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019f660f-6aa0-7209-8b13-cc270691f8ef" xlink:to="loc_us-gaap_SegmentDomain_019f660f-6aa0-7209-8b13-cc270691f8ef_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019f660f-6aa0-793d-ab3c-799df247e3b7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019f660f-6aa0-7209-8b13-cc270691f8ef" xlink:to="loc_us-gaap_SegmentDomain_019f660f-6aa0-793d-ab3c-799df247e3b7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_UASMember_019f660f-6aa0-760e-8178-538718a4e510" xlink:href="xtia-20260630.xsd#xtia_UASMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019f660f-6aa0-793d-ab3c-799df247e3b7" xlink:to="loc_xtia_UASMember_019f660f-6aa0-760e-8178-538718a4e510" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_ADSMember_019f660f-6aa0-7ff8-80ef-d5011075541a" xlink:href="xtia-20260630.xsd#xtia_ADSMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019f660f-6aa0-793d-ab3c-799df247e3b7" xlink:to="loc_xtia_ADSMember_019f660f-6aa0-7ff8-80ef-d5011075541a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_CommercialAviationMember_019f660f-6aa0-72b2-b496-1b3f5f61cf04" xlink:href="xtia-20260630.xsd#xtia_CommercialAviationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019f660f-6aa0-793d-ab3c-799df247e3b7" xlink:to="loc_xtia_CommercialAviationMember_019f660f-6aa0-72b2-b496-1b3f5f61cf04" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementScenarioAxis_01a15adf-4cb7-717d-8da0-95431a0e3628" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_StatementScenarioAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019f660f-6aa0-73c9-b31a-16dfafba3634" xlink:to="loc_srt_StatementScenarioAxis_01a15adf-4cb7-717d-8da0-95431a0e3628" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_01a15adf-4cb7-717d-8da0-95431a0e3628_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementScenarioAxis_01a15adf-4cb7-717d-8da0-95431a0e3628" xlink:to="loc_srt_ScenarioUnspecifiedDomain_01a15adf-4cb7-717d-8da0-95431a0e3628_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_01a15adf-4cb7-7623-897e-753a7cdccef3" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementScenarioAxis_01a15adf-4cb7-717d-8da0-95431a0e3628" xlink:to="loc_srt_ScenarioUnspecifiedDomain_01a15adf-4cb7-7623-897e-753a7cdccef3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_ScenarioRoundingMember_01a15adf-859d-7f0c-9b0b-6a2275aa9515" xlink:href="xtia-20260630.xsd#xtia_ScenarioRoundingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ScenarioUnspecifiedDomain_01a15adf-4cb7-7623-897e-753a7cdccef3" xlink:to="loc_xtia_ScenarioRoundingMember_01a15adf-859d-7f0c-9b0b-6a2275aa9515" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_019f660f-6aa0-71af-87e5-3ea0dcd7352a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f660f-6aa0-70ec-af0e-1d9a94d4fcfd" xlink:to="loc_us-gaap_Revenues_019f660f-6aa0-71af-87e5-3ea0dcd7352a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfRevenue_019f660f-6aa0-74ff-b0cb-572f086aa68b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CostOfRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f660f-6aa0-70ec-af0e-1d9a94d4fcfd" xlink:to="loc_us-gaap_CostOfRevenue_019f660f-6aa0-74ff-b0cb-572f086aa68b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingExpensesAbstract_019f660f-6aa0-7dc5-8c2b-7ca46688cdeb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingExpensesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f660f-6aa0-70ec-af0e-1d9a94d4fcfd" xlink:to="loc_us-gaap_OperatingExpensesAbstract_019f660f-6aa0-7dc5-8c2b-7ca46688cdeb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_ResearchAndDevelopmentExpenseExcludingShareBasedCompensationExpense_01a0c9d4-8c4a-701e-b1ac-c0e762e9ab44" xlink:href="xtia-20260630.xsd#xtia_ResearchAndDevelopmentExpenseExcludingShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_019f660f-6aa0-7dc5-8c2b-7ca46688cdeb" xlink:to="loc_xtia_ResearchAndDevelopmentExpenseExcludingShareBasedCompensationExpense_01a0c9d4-8c4a-701e-b1ac-c0e762e9ab44" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_SellingAndMarketingExpenseExcludingShareBasedCompensationExpense_01a0c9d2-89ce-7b13-88ef-6b505fb90562" xlink:href="xtia-20260630.xsd#xtia_SellingAndMarketingExpenseExcludingShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_019f660f-6aa0-7dc5-8c2b-7ca46688cdeb" xlink:to="loc_xtia_SellingAndMarketingExpenseExcludingShareBasedCompensationExpense_01a0c9d2-89ce-7b13-88ef-6b505fb90562" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_GeneralAndAdministrativeExpenseExcludingShareBasedCompensationExpense_01a0c9d6-a4b3-7b52-a106-0dc5395b4c10" xlink:href="xtia-20260630.xsd#xtia_GeneralAndAdministrativeExpenseExcludingShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_019f660f-6aa0-7dc5-8c2b-7ca46688cdeb" xlink:to="loc_xtia_GeneralAndAdministrativeExpenseExcludingShareBasedCompensationExpense_01a0c9d6-a4b3-7b52-a106-0dc5395b4c10" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherGeneralExpense_019f660f-6aa0-74a3-9c16-0c37015e855f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherGeneralExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_019f660f-6aa0-7dc5-8c2b-7ca46688cdeb" xlink:to="loc_us-gaap_OtherGeneralExpense_019f660f-6aa0-74a3-9c16-0c37015e855f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingExpenses_019f660f-6aa0-7b2b-a4e8-82d260d2a4a0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_019f660f-6aa0-7dc5-8c2b-7ca46688cdeb" xlink:to="loc_us-gaap_OperatingExpenses_019f660f-6aa0-7b2b-a4e8-82d260d2a4a0" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_EarningsBeforeInterestTaxDepreciationAndAmortization_01a0c444-4aee-7b64-919b-b3c30d743882" xlink:href="xtia-20260630.xsd#xtia_EarningsBeforeInterestTaxDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f660f-6aa0-70ec-af0e-1d9a94d4fcfd" xlink:to="loc_xtia_EarningsBeforeInterestTaxDepreciationAndAmortization_01a0c444-4aee-7b64-919b-b3c30d743882" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_019f660f-6aa0-786b-991f-4f0b74fb9841" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f660f-6aa0-70ec-af0e-1d9a94d4fcfd" xlink:to="loc_us-gaap_OperatingIncomeLoss_019f660f-6aa0-786b-991f-4f0b74fb9841" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepreciationDepletionAndAmortization_01a0c444-faa0-739a-8a17-284329465458" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DepreciationDepletionAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f660f-6aa0-70ec-af0e-1d9a94d4fcfd" xlink:to="loc_us-gaap_DepreciationDepletionAndAmortization_01a0c444-faa0-739a-8a17-284329465458" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseNonoperating_01a0c9c2-08d7-758f-8947-1dad9733db96" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestExpenseNonoperating"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f660f-6aa0-70ec-af0e-1d9a94d4fcfd" xlink:to="loc_us-gaap_InterestExpenseNonoperating_01a0c9c2-08d7-758f-8947-1dad9733db96" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncashMergerRelatedCosts_01a0c9c2-08d7-7934-8247-647360fa66a9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NoncashMergerRelatedCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f660f-6aa0-70ec-af0e-1d9a94d4fcfd" xlink:to="loc_us-gaap_NoncashMergerRelatedCosts_01a0c9c2-08d7-7934-8247-647360fa66a9" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_01a0c9c0-6957-7152-9885-2dc16e216c77" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f660f-6aa0-70ec-af0e-1d9a94d4fcfd" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_01a0c9c0-6957-7152-9885-2dc16e216c77" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAdjustmentOfWarrants_01a0c9c2-08d7-7df1-84af-d964dcb0a028" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAdjustmentOfWarrants"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f660f-6aa0-70ec-af0e-1d9a94d4fcfd" xlink:to="loc_us-gaap_FairValueAdjustmentOfWarrants_01a0c9c2-08d7-7df1-84af-d964dcb0a028" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpense_01a0c9c2-08d7-7e00-b8c5-314968e9c8e6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherNonoperatingIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f660f-6aa0-70ec-af0e-1d9a94d4fcfd" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpense_01a0c9c2-08d7-7e00-b8c5-314968e9c8e6" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonoperatingIncomeExpense_01a01a68-dfa3-79a9-beba-7260a16896a5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NonoperatingIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f660f-6aa0-70ec-af0e-1d9a94d4fcfd" xlink:to="loc_us-gaap_NonoperatingIncomeExpense_01a01a68-dfa3-79a9-beba-7260a16896a5" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_01a000ea-d349-763d-955f-0e82c9769d02" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f660f-6aa0-70ec-af0e-1d9a94d4fcfd" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_01a000ea-d349-763d-955f-0e82c9769d02" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_01a000ea-d349-744f-b2a7-476ac41bab35" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f660f-6aa0-70ec-af0e-1d9a94d4fcfd" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_01a000ea-d349-744f-b2a7-476ac41bab35" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest_01a000ea-d349-75e8-b6d4-ab83434a9228" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019f660f-6aa0-70ec-af0e-1d9a94d4fcfd" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest_01a000ea-d349-75e8-b6d4-ab83434a9228" xlink:type="arc" order="14"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.xtiaircraft.com/role/FairValueMeasurementsandFairValueofFinancialInstrumentsNarrativeDetails" xlink:type="simple" xlink:href="xtia-20260630.xsd#FairValueMeasurementsandFairValueofFinancialInstrumentsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.xtiaircraft.com/role/FairValueMeasurementsandFairValueofFinancialInstrumentsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019f660f-6aa0-7656-8ece-7ad1961dd139" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_FairValueMeasurementsandFairValueofFinancialInstrumentsDetailsTable_019f660f-6aa0-784f-a446-8c1883553fd3" xlink:href="xtia-20260630.xsd#xtia_FairValueMeasurementsandFairValueofFinancialInstrumentsDetailsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019f660f-6aa0-7656-8ece-7ad1961dd139" xlink:to="loc_xtia_FairValueMeasurementsandFairValueofFinancialInstrumentsDetailsTable_019f660f-6aa0-784f-a446-8c1883553fd3" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019f660f-6aa0-7ace-bec0-b533cd652c54" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_xtia_FairValueMeasurementsandFairValueofFinancialInstrumentsDetailsTable_019f660f-6aa0-784f-a446-8c1883553fd3" xlink:to="loc_srt_RangeAxis_019f660f-6aa0-7ace-bec0-b533cd652c54" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019f660f-6aa0-7ace-bec0-b533cd652c54_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019f660f-6aa0-7ace-bec0-b533cd652c54" xlink:to="loc_srt_RangeMember_019f660f-6aa0-7ace-bec0-b533cd652c54_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019f660f-6aa0-723f-9181-0cf5d9f06af7" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019f660f-6aa0-7ace-bec0-b533cd652c54" xlink:to="loc_srt_RangeMember_019f660f-6aa0-723f-9181-0cf5d9f06af7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019f660f-6aa0-77c8-bbf9-547be48f5db9" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019f660f-6aa0-723f-9181-0cf5d9f06af7" xlink:to="loc_srt_MinimumMember_019f660f-6aa0-77c8-bbf9-547be48f5db9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019f660f-6aa0-7b8f-9554-9a070f9d0c83" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019f660f-6aa0-723f-9181-0cf5d9f06af7" xlink:to="loc_srt_MaximumMember_019f660f-6aa0-7b8f-9554-9a070f9d0c83" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeAxis_019f660f-6aa0-7472-8991-dede4ea46434" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_xtia_FairValueMeasurementsandFairValueofFinancialInstrumentsDetailsTable_019f660f-6aa0-784f-a446-8c1883553fd3" xlink:to="loc_us-gaap_MeasurementInputTypeAxis_019f660f-6aa0-7472-8991-dede4ea46434" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeDomain_019f660f-6aa0-7472-8991-dede4ea46434_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_MeasurementInputTypeAxis_019f660f-6aa0-7472-8991-dede4ea46434" xlink:to="loc_us-gaap_MeasurementInputTypeDomain_019f660f-6aa0-7472-8991-dede4ea46434_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeDomain_019f660f-6aa0-71b1-a53d-bf0054c56076" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_MeasurementInputTypeAxis_019f660f-6aa0-7472-8991-dede4ea46434" xlink:to="loc_us-gaap_MeasurementInputTypeDomain_019f660f-6aa0-71b1-a53d-bf0054c56076" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputSharePriceMember_019f660f-6aa0-7272-8bd4-a73c85280000" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputSharePriceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_019f660f-6aa0-71b1-a53d-bf0054c56076" xlink:to="loc_us-gaap_MeasurementInputSharePriceMember_019f660f-6aa0-7272-8bd4-a73c85280000" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputExercisePriceMember_019f660f-6aa0-7844-9b37-6a1e00c2cfdf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputExercisePriceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_019f660f-6aa0-71b1-a53d-bf0054c56076" xlink:to="loc_us-gaap_MeasurementInputExercisePriceMember_019f660f-6aa0-7844-9b37-6a1e00c2cfdf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputPriceVolatilityMember_019f660f-6aa0-70db-867d-5b4c78425ed3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputPriceVolatilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_019f660f-6aa0-71b1-a53d-bf0054c56076" xlink:to="loc_us-gaap_MeasurementInputPriceVolatilityMember_019f660f-6aa0-70db-867d-5b4c78425ed3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputRiskFreeInterestRateMember_019f660f-6aa0-7532-b5f0-c5eab949facf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputRiskFreeInterestRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_019f660f-6aa0-71b1-a53d-bf0054c56076" xlink:to="loc_us-gaap_MeasurementInputRiskFreeInterestRateMember_019f660f-6aa0-7532-b5f0-c5eab949facf" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputExpectedTermMember_019f660f-6aa0-771e-81cc-d718eca87579" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputExpectedTermMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_019f660f-6aa0-71b1-a53d-bf0054c56076" xlink:to="loc_us-gaap_MeasurementInputExpectedTermMember_019f660f-6aa0-771e-81cc-d718eca87579" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputExpectedDividendRateMember_019f660f-6aa0-7362-8706-fd24d3390caf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MeasurementInputExpectedDividendRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_019f660f-6aa0-71b1-a53d-bf0054c56076" xlink:to="loc_us-gaap_MeasurementInputExpectedDividendRateMember_019f660f-6aa0-7362-8706-fd24d3390caf" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightAxis_019f660f-6aa0-7d1f-b736-6cd1285dcd3b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_xtia_FairValueMeasurementsandFairValueofFinancialInstrumentsDetailsTable_019f660f-6aa0-784f-a446-8c1883553fd3" xlink:to="loc_us-gaap_ClassOfWarrantOrRightAxis_019f660f-6aa0-7d1f-b736-6cd1285dcd3b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightDomain_019f660f-6aa0-7d1f-b736-6cd1285dcd3b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ClassOfWarrantOrRightAxis_019f660f-6aa0-7d1f-b736-6cd1285dcd3b" xlink:to="loc_us-gaap_ClassOfWarrantOrRightDomain_019f660f-6aa0-7d1f-b736-6cd1285dcd3b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightDomain_019f660f-6aa0-7b64-99de-dc44c5a868e5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ClassOfWarrantOrRightAxis_019f660f-6aa0-7d1f-b736-6cd1285dcd3b" xlink:to="loc_us-gaap_ClassOfWarrantOrRightDomain_019f660f-6aa0-7b64-99de-dc44c5a868e5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WarrantMember_019f660f-6aa0-7ee3-8b80-721ab9b1eec2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WarrantMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightDomain_019f660f-6aa0-7b64-99de-dc44c5a868e5" xlink:to="loc_us-gaap_WarrantMember_019f660f-6aa0-7ee3-8b80-721ab9b1eec2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WarrantsAndRightsOutstandingMeasurementInput_019f660f-6aa0-73a3-b462-c13028e28808" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WarrantsAndRightsOutstandingMeasurementInput"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019f660f-6aa0-7656-8ece-7ad1961dd139" xlink:to="loc_us-gaap_WarrantsAndRightsOutstandingMeasurementInput_019f660f-6aa0-73a3-b462-c13028e28808" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.xtiaircraft.com/role/FairValueMeasurementsandFairValueofFinancialInstrumentsScheduleofFairValueConsistedAssetsandLiabilitiesDetails" xlink:type="simple" xlink:href="xtia-20260630.xsd#FairValueMeasurementsandFairValueofFinancialInstrumentsScheduleofFairValueConsistedAssetsandLiabilitiesDetails"/>
  <link:definitionLink xlink:role="http://www.xtiaircraft.com/role/FairValueMeasurementsandFairValueofFinancialInstrumentsScheduleofFairValueConsistedAssetsandLiabilitiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_xtia_FairValueMeasurementsAndFairValueOfFinancialInstrumentsScheduleOfFairValueConsistedAssetsAndLiabilitiesDetailsLineItems_019f660f-6aa0-7c11-86cb-19e27cc5fc7e" xlink:href="xtia-20260630.xsd#xtia_FairValueMeasurementsAndFairValueOfFinancialInstrumentsScheduleOfFairValueConsistedAssetsAndLiabilitiesDetailsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_FairValueMeasurementsandFairValueofFinancialInstrumentsScheduleofFairValueConsistedAssetsandLiabilitiesDetailsTable_019f660f-6aa0-7dc8-bc14-a26b0316bcdf" xlink:href="xtia-20260630.xsd#xtia_FairValueMeasurementsandFairValueofFinancialInstrumentsScheduleofFairValueConsistedAssetsandLiabilitiesDetailsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_xtia_FairValueMeasurementsAndFairValueOfFinancialInstrumentsScheduleOfFairValueConsistedAssetsAndLiabilitiesDetailsLineItems_019f660f-6aa0-7c11-86cb-19e27cc5fc7e" xlink:to="loc_xtia_FairValueMeasurementsandFairValueofFinancialInstrumentsScheduleofFairValueConsistedAssetsandLiabilitiesDetailsTable_019f660f-6aa0-7dc8-bc14-a26b0316bcdf" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019f660f-6aa0-7841-98fa-b2530d73a0b5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_xtia_FairValueMeasurementsandFairValueofFinancialInstrumentsScheduleofFairValueConsistedAssetsandLiabilitiesDetailsTable_019f660f-6aa0-7dc8-bc14-a26b0316bcdf" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019f660f-6aa0-7841-98fa-b2530d73a0b5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019f660f-6aa0-7841-98fa-b2530d73a0b5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019f660f-6aa0-7841-98fa-b2530d73a0b5" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019f660f-6aa0-7841-98fa-b2530d73a0b5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019f660f-6aa0-7663-9f53-49aacc3b7ecb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019f660f-6aa0-7841-98fa-b2530d73a0b5" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019f660f-6aa0-7663-9f53-49aacc3b7ecb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_019f660f-6aa0-7703-9277-40baeff7caff" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019f660f-6aa0-7663-9f53-49aacc3b7ecb" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_019f660f-6aa0-7703-9277-40baeff7caff" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_019f660f-6aa0-7eff-b649-b5551d218ca5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019f660f-6aa0-7663-9f53-49aacc3b7ecb" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_019f660f-6aa0-7eff-b649-b5551d218ca5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_019f660f-6aa0-7fa7-828b-da77b755ef13" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019f660f-6aa0-7663-9f53-49aacc3b7ecb" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_019f660f-6aa0-7fa7-828b-da77b755ef13" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_019f660f-6aa0-785b-b77c-4824b2cbc916" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_xtia_FairValueMeasurementsandFairValueofFinancialInstrumentsScheduleofFairValueConsistedAssetsandLiabilitiesDetailsTable_019f660f-6aa0-7dc8-bc14-a26b0316bcdf" xlink:to="loc_us-gaap_FinancialInstrumentAxis_019f660f-6aa0-785b-b77c-4824b2cbc916" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019f660f-6aa0-785b-b77c-4824b2cbc916_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019f660f-6aa0-785b-b77c-4824b2cbc916" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019f660f-6aa0-785b-b77c-4824b2cbc916_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019f660f-6aa0-71c0-9dc9-0b81b0859363" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019f660f-6aa0-785b-b77c-4824b2cbc916" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019f660f-6aa0-71c0-9dc9-0b81b0859363" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WarrantMember_019f660f-6aa0-75da-ac5f-e0fd73c0cbca" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WarrantMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019f660f-6aa0-71c0-9dc9-0b81b0859363" xlink:to="loc_us-gaap_WarrantMember_019f660f-6aa0-75da-ac5f-e0fd73c0cbca" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WarrantsAndRightsOutstanding_019f660f-6aa0-79a2-ac86-b840e96843ee" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WarrantsAndRightsOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_xtia_FairValueMeasurementsAndFairValueOfFinancialInstrumentsScheduleOfFairValueConsistedAssetsAndLiabilitiesDetailsLineItems_019f660f-6aa0-7c11-86cb-19e27cc5fc7e" xlink:to="loc_us-gaap_WarrantsAndRightsOutstanding_019f660f-6aa0-79a2-ac86-b840e96843ee" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialLiabilitiesFairValueDisclosure_019fcdc6-5dfe-7446-9c36-1f64901175f3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancialLiabilitiesFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_xtia_FairValueMeasurementsAndFairValueOfFinancialInstrumentsScheduleOfFairValueConsistedAssetsAndLiabilitiesDetailsLineItems_019f660f-6aa0-7c11-86cb-19e27cc5fc7e" xlink:to="loc_us-gaap_FinancialLiabilitiesFairValueDisclosure_019fcdc6-5dfe-7446-9c36-1f64901175f3" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.xtiaircraft.com/role/FairValueMeasurementsandFairValueofFinancialInstrumentsScheduleofReconciliationofLiabilitiesforLevel3InvestmentsDetails" xlink:type="simple" xlink:href="xtia-20260630.xsd#FairValueMeasurementsandFairValueofFinancialInstrumentsScheduleofReconciliationofLiabilitiesforLevel3InvestmentsDetails"/>
  <link:definitionLink xlink:role="http://www.xtiaircraft.com/role/FairValueMeasurementsandFairValueofFinancialInstrumentsScheduleofReconciliationofLiabilitiesforLevel3InvestmentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_019f660f-6aa0-7362-acd8-a7c0405fdfb0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019f660f-6aa0-76b0-b48d-85ee8491860e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_019f660f-6aa0-7362-acd8-a7c0405fdfb0" xlink:to="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019f660f-6aa0-76b0-b48d-85ee8491860e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightAxis_019f660f-6aa0-7c07-ba68-376207a75581" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019f660f-6aa0-76b0-b48d-85ee8491860e" xlink:to="loc_us-gaap_ClassOfWarrantOrRightAxis_019f660f-6aa0-7c07-ba68-376207a75581" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightDomain_019f660f-6aa0-7c07-ba68-376207a75581_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ClassOfWarrantOrRightAxis_019f660f-6aa0-7c07-ba68-376207a75581" xlink:to="loc_us-gaap_ClassOfWarrantOrRightDomain_019f660f-6aa0-7c07-ba68-376207a75581_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfWarrantOrRightDomain_019f660f-6aa0-758f-93fb-fded1fc1ab2a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ClassOfWarrantOrRightAxis_019f660f-6aa0-7c07-ba68-376207a75581" xlink:to="loc_us-gaap_ClassOfWarrantOrRightDomain_019f660f-6aa0-758f-93fb-fded1fc1ab2a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_EquityInvestmentValkyrieSciencesLLCMember_019f660f-6aa0-7710-9f54-b582d3ef4804" xlink:href="xtia-20260630.xsd#xtia_EquityInvestmentValkyrieSciencesLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfWarrantOrRightDomain_019f660f-6aa0-758f-93fb-fded1fc1ab2a" xlink:to="loc_xtia_EquityInvestmentValkyrieSciencesLLCMember_019f660f-6aa0-7710-9f54-b582d3ef4804" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019f660f-6aa0-7cb8-b17a-a5ea9d6aa0b0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019f660f-6aa0-76b0-b48d-85ee8491860e" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019f660f-6aa0-7cb8-b17a-a5ea9d6aa0b0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019f660f-6aa0-7cb8-b17a-a5ea9d6aa0b0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019f660f-6aa0-7cb8-b17a-a5ea9d6aa0b0" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019f660f-6aa0-7cb8-b17a-a5ea9d6aa0b0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019f660f-6aa0-732c-8f50-ddd2dc987bdc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019f660f-6aa0-7cb8-b17a-a5ea9d6aa0b0" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019f660f-6aa0-732c-8f50-ddd2dc987bdc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_019f660f-6aa0-7093-b245-4eda237fb7c1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019f660f-6aa0-732c-8f50-ddd2dc987bdc" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_019f660f-6aa0-7093-b245-4eda237fb7c1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilities_019f660f-6aa0-724a-880d-f81a34a6fecc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_019f660f-6aa0-7362-acd8-a7c0405fdfb0" xlink:to="loc_us-gaap_DerivativeLiabilities_019f660f-6aa0-724a-880d-f81a34a6fecc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_WarrantsIssuedInConnectionWithTheSeptemberOffering_019f660f-6aa0-777c-8448-9114f0db005e" xlink:href="xtia-20260630.xsd#xtia_WarrantsIssuedInConnectionWithTheSeptemberOffering"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_019f660f-6aa0-7362-acd8-a7c0405fdfb0" xlink:to="loc_xtia_WarrantsIssuedInConnectionWithTheSeptemberOffering_019f660f-6aa0-777c-8448-9114f0db005e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_StockIssuedDuringPeriodValueIssuedForExerciseOfWarrants_019f660f-6aa0-7aa4-a3d1-8ae5b87f2d96" xlink:href="xtia-20260630.xsd#xtia_StockIssuedDuringPeriodValueIssuedForExerciseOfWarrants"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_019f660f-6aa0-7362-acd8-a7c0405fdfb0" xlink:to="loc_xtia_StockIssuedDuringPeriodValueIssuedForExerciseOfWarrants_019f660f-6aa0-7aa4-a3d1-8ae5b87f2d96" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityChangeInFairValue_019f660f-6aa0-70b6-a0c6-42dfdbee8105" xlink:href="xtia-20260630.xsd#xtia_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityChangeInFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_019f660f-6aa0-7362-acd8-a7c0405fdfb0" xlink:to="loc_xtia_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityChangeInFairValue_019f660f-6aa0-70b6-a0c6-42dfdbee8105" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilities_019f660f-6aa0-78fb-b2a2-d7ba15ce83c9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLiabilities"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.xtiaircraft.com/role/CommitmentsandContingenciesDetails" xlink:type="simple" xlink:href="xtia-20260630.xsd#CommitmentsandContingenciesDetails"/>
  <link:definitionLink xlink:role="http://www.xtiaircraft.com/role/CommitmentsandContingenciesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsLineItems_019f660f-6aa0-74ee-99c7-0a883fa0be10" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherCommitmentsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_CommitmentsandContingenciesDetailsTable_019f660f-6aa0-7e32-8a30-47a05784bb7c" xlink:href="xtia-20260630.xsd#xtia_CommitmentsandContingenciesDetailsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_019f660f-6aa0-74ee-99c7-0a883fa0be10" xlink:to="loc_xtia_CommitmentsandContingenciesDetailsTable_019f660f-6aa0-7e32-8a30-47a05784bb7c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseAxis_019f660f-6aa0-7db9-81ec-925e238003de" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_LitigationCaseAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_xtia_CommitmentsandContingenciesDetailsTable_019f660f-6aa0-7e32-8a30-47a05784bb7c" xlink:to="loc_srt_LitigationCaseAxis_019f660f-6aa0-7db9-81ec-925e238003de" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_019f660f-6aa0-7db9-81ec-925e238003de_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_LitigationCaseAxis_019f660f-6aa0-7db9-81ec-925e238003de" xlink:to="loc_srt_LitigationCaseTypeDomain_019f660f-6aa0-7db9-81ec-925e238003de_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_019f660f-6aa0-709a-b95d-a3663c1c1096" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_LitigationCaseAxis_019f660f-6aa0-7db9-81ec-925e238003de" xlink:to="loc_srt_LitigationCaseTypeDomain_019f660f-6aa0-709a-b95d-a3663c1c1096" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_XeriantLitigationMember_019f660f-6aa0-7629-b74c-c7e68af46c54" xlink:href="xtia-20260630.xsd#xtia_XeriantLitigationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_019f660f-6aa0-709a-b95d-a3663c1c1096" xlink:to="loc_xtia_XeriantLitigationMember_019f660f-6aa0-7629-b74c-c7e68af46c54" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_019f660f-6aa0-70e8-973c-6eaf52c44a23" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_xtia_CommitmentsandContingenciesDetailsTable_019f660f-6aa0-7e32-8a30-47a05784bb7c" xlink:to="loc_dei_LegalEntityAxis_019f660f-6aa0-70e8-973c-6eaf52c44a23" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019f660f-6aa0-70e8-973c-6eaf52c44a23_default" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_019f660f-6aa0-70e8-973c-6eaf52c44a23" xlink:to="loc_dei_EntityDomain_019f660f-6aa0-70e8-973c-6eaf52c44a23_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_019f660f-6aa0-70ce-b6d0-1694c960134a" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_019f660f-6aa0-70e8-973c-6eaf52c44a23" xlink:to="loc_dei_EntityDomain_019f660f-6aa0-70ce-b6d0-1694c960134a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_XeriantIncMember_019f660f-6aa0-7bec-bcc9-3e2242fa34e7" xlink:href="xtia-20260630.xsd#xtia_XeriantIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_019f660f-6aa0-70ce-b6d0-1694c960134a" xlink:to="loc_xtia_XeriantIncMember_019f660f-6aa0-7bec-bcc9-3e2242fa34e7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019f660f-6aa0-7a96-9200-6ed4abbcbb7e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_xtia_CommitmentsandContingenciesDetailsTable_019f660f-6aa0-7e32-8a30-47a05784bb7c" xlink:to="loc_us-gaap_DebtInstrumentAxis_019f660f-6aa0-7a96-9200-6ed4abbcbb7e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019f660f-6aa0-7a96-9200-6ed4abbcbb7e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_019f660f-6aa0-7a96-9200-6ed4abbcbb7e" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019f660f-6aa0-7a96-9200-6ed4abbcbb7e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019f660f-6aa0-7a67-991f-69568e86457a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_019f660f-6aa0-7a96-9200-6ed4abbcbb7e" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019f660f-6aa0-7a67-991f-69568e86457a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_SeniorSecuredPromissoryNoteMember_019f660f-6aa0-7fc8-a158-83d35e440409" xlink:href="xtia-20260630.xsd#xtia_SeniorSecuredPromissoryNoteMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019f660f-6aa0-7a67-991f-69568e86457a" xlink:to="loc_xtia_SeniorSecuredPromissoryNoteMember_019f660f-6aa0-7fc8-a158-83d35e440409" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_019f660f-6aa0-7d23-b92b-5eee54a0761f" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_xtia_CommitmentsandContingenciesDetailsTable_019f660f-6aa0-7e32-8a30-47a05784bb7c" xlink:to="loc_srt_CounterpartyNameAxis_019f660f-6aa0-7d23-b92b-5eee54a0761f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019f660f-6aa0-7d23-b92b-5eee54a0761f_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_019f660f-6aa0-7d23-b92b-5eee54a0761f" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019f660f-6aa0-7d23-b92b-5eee54a0761f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019f660f-6aa0-72c5-8aeb-fc55e00216e0" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_019f660f-6aa0-7d23-b92b-5eee54a0761f" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019f660f-6aa0-72c5-8aeb-fc55e00216e0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_AuctusFundLLCMember_019f660f-6aa0-7419-9a7e-905ee2e0d20b" xlink:href="xtia-20260630.xsd#xtia_AuctusFundLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019f660f-6aa0-72c5-8aeb-fc55e00216e0" xlink:to="loc_xtia_AuctusFundLLCMember_019f660f-6aa0-7419-9a7e-905ee2e0d20b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_01a13180-511e-7232-bc9e-3faa99d84438" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_xtia_CommitmentsandContingenciesDetailsTable_019f660f-6aa0-7e32-8a30-47a05784bb7c" xlink:to="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_01a13180-511e-7232-bc9e-3faa99d84438" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_01a13180-511e-7232-bc9e-3faa99d84438_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_01a13180-511e-7232-bc9e-3faa99d84438" xlink:to="loc_us-gaap_LossContingencyNatureDomain_01a13180-511e-7232-bc9e-3faa99d84438_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_01a13180-511e-7900-8e6b-c0e36d299e03" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_01a13180-511e-7232-bc9e-3faa99d84438" xlink:to="loc_us-gaap_LossContingencyNatureDomain_01a13180-511e-7900-8e6b-c0e36d299e03" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_OtherLossContingenciesMember_01a13180-7e9d-7e86-a690-1b0a03baa069" xlink:href="xtia-20260630.xsd#xtia_OtherLossContingenciesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_01a13180-511e-7900-8e6b-c0e36d299e03" xlink:to="loc_xtia_OtherLossContingenciesMember_01a13180-7e9d-7e86-a690-1b0a03baa069" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyDamagesSoughtValue_019f660f-6aa0-782a-b694-6bc50a9799b7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyDamagesSoughtValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_019f660f-6aa0-74ee-99c7-0a883fa0be10" xlink:to="loc_us-gaap_LossContingencyDamagesSoughtValue_019f660f-6aa0-782a-b694-6bc50a9799b7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_019f660f-6aa0-74d1-8e0f-8ec765ebbbde" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_019f660f-6aa0-74ee-99c7-0a883fa0be10" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_019f660f-6aa0-74d1-8e0f-8ec765ebbbde" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyAccrualAtCarryingValue_019f660f-6aa0-7c26-8531-9328aee7f8b5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingencyAccrualAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_019f660f-6aa0-74ee-99c7-0a883fa0be10" xlink:to="loc_us-gaap_LossContingencyAccrualAtCarryingValue_019f660f-6aa0-7c26-8531-9328aee7f8b5" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.xtiaircraft.com/role/NetLossPerShareAttributabletoCommonStockholdersScheduleofAntidilutiveSecuritiesExcludedfromComputationofDilutedNetLossPerShareDetails" xlink:type="simple" xlink:href="xtia-20260630.xsd#NetLossPerShareAttributabletoCommonStockholdersScheduleofAntidilutiveSecuritiesExcludedfromComputationofDilutedNetLossPerShareDetails"/>
  <link:definitionLink xlink:role="http://www.xtiaircraft.com/role/NetLossPerShareAttributabletoCommonStockholdersScheduleofAntidilutiveSecuritiesExcludedfromComputationofDilutedNetLossPerShareDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_019f660f-6aa0-7adc-b5d1-d24fd7c5184b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_019f660f-6aa0-7b13-92da-3869017b116f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_019f660f-6aa0-7adc-b5d1-d24fd7c5184b" xlink:to="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_019f660f-6aa0-7b13-92da-3869017b116f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_019f660f-6aa0-7d29-995b-9544c81a523b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_019f660f-6aa0-7b13-92da-3869017b116f" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_019f660f-6aa0-7d29-995b-9544c81a523b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019f660f-6aa0-7d29-995b-9544c81a523b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_019f660f-6aa0-7d29-995b-9544c81a523b" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019f660f-6aa0-7d29-995b-9544c81a523b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019f660f-6aa0-723e-aba0-2b2db5b99000" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_019f660f-6aa0-7d29-995b-9544c81a523b" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019f660f-6aa0-723e-aba0-2b2db5b99000" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockOptionMember_019f660f-6aa0-7346-9d53-273d36851af7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019f660f-6aa0-723e-aba0-2b2db5b99000" xlink:to="loc_us-gaap_StockOptionMember_019f660f-6aa0-7346-9d53-273d36851af7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WarrantMember_019f660f-6aa0-7940-9512-3446f7a90cbc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WarrantMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019f660f-6aa0-723e-aba0-2b2db5b99000" xlink:to="loc_us-gaap_WarrantMember_019f660f-6aa0-7940-9512-3446f7a90cbc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConvertiblePreferredStockMember_019f660f-6aa0-767a-bdb0-db3e3eb2b759" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConvertiblePreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019f660f-6aa0-723e-aba0-2b2db5b99000" xlink:to="loc_us-gaap_ConvertiblePreferredStockMember_019f660f-6aa0-767a-bdb0-db3e3eb2b759" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_NoncontrollingInterestClassBUnitsMember_019f660f-6aa0-72fb-8113-7754ea6acb84" xlink:href="xtia-20260630.xsd#xtia_NoncontrollingInterestClassBUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019f660f-6aa0-723e-aba0-2b2db5b99000" xlink:to="loc_xtia_NoncontrollingInterestClassBUnitsMember_019f660f-6aa0-72fb-8113-7754ea6acb84" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_019f660f-6aa0-710c-b109-fb1458191ab7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_019f660f-6aa0-7adc-b5d1-d24fd7c5184b" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_019f660f-6aa0-710c-b109-fb1458191ab7" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.xtiaircraft.com/role/IncomeTaxesDetails" xlink:type="simple" xlink:href="xtia-20260630.xsd#IncomeTaxesDetails"/>
  <link:definitionLink xlink:role="http://www.xtiaircraft.com/role/IncomeTaxesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationLineItems_019fec6d-63b5-7c9a-a400-c82fa3142159" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationTable_019fec6d-63b5-7bb9-9cbc-06f29f6c83f9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateReconciliationLineItems_019fec6d-63b5-7c9a-a400-c82fa3142159" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateReconciliationTable_019fec6d-63b5-7bb9-9cbc-06f29f6c83f9" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementOperatingActivitiesSegmentAxis_019fec6d-63b5-7848-934d-436ad4660c35" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementOperatingActivitiesSegmentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateReconciliationTable_019fec6d-63b5-7bb9-9cbc-06f29f6c83f9" xlink:to="loc_us-gaap_StatementOperatingActivitiesSegmentAxis_019fec6d-63b5-7848-934d-436ad4660c35" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentOperatingActivitiesDomain_019fec6d-63b5-7848-934d-436ad4660c35_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentOperatingActivitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementOperatingActivitiesSegmentAxis_019fec6d-63b5-7848-934d-436ad4660c35" xlink:to="loc_us-gaap_SegmentOperatingActivitiesDomain_019fec6d-63b5-7848-934d-436ad4660c35_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentOperatingActivitiesDomain_019fec6d-63b5-78b3-8f2b-98055347fadb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentOperatingActivitiesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementOperatingActivitiesSegmentAxis_019fec6d-63b5-7848-934d-436ad4660c35" xlink:to="loc_us-gaap_SegmentOperatingActivitiesDomain_019fec6d-63b5-78b3-8f2b-98055347fadb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDiscontinuedOperationsMember_019fec6d-b42b-7a27-a98a-8311b6572232" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDiscontinuedOperationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentOperatingActivitiesDomain_019fec6d-63b5-78b3-8f2b-98055347fadb" xlink:to="loc_us-gaap_SegmentDiscontinuedOperationsMember_019fec6d-b42b-7a27-a98a-8311b6572232" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_019fec6d-63b5-7cf3-b11f-f782addb05ed" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateReconciliationLineItems_019fec6d-63b5-7c9a-a400-c82fa3142159" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_019fec6d-63b5-7cf3-b11f-f782addb05ed" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperations_019f859d-3d29-73f3-a545-3c95a325b266" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EffectiveIncomeTaxRateContinuingOperations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EffectiveIncomeTaxRateReconciliationLineItems_019fec6d-63b5-7c9a-a400-c82fa3142159" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperations_019f859d-3d29-73f3-a545-3c95a325b266" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.xtiaircraft.com/role/RelatedPartiesDetails" xlink:type="simple" xlink:href="xtia-20260630.xsd#RelatedPartiesDetails"/>
  <link:definitionLink xlink:role="http://www.xtiaircraft.com/role/RelatedPartiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionLineItems_01a1542d-9fb7-703b-a71f-dd0ac344cf00" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyTransactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_01a01532-1934-7706-a194-5c0234d95298" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_01a1542d-9fb7-703b-a71f-dd0ac344cf00" xlink:to="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_01a01532-1934-7706-a194-5c0234d95298" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_01a15aa3-1087-7623-b946-bc2b0475d99e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_01a01532-1934-7706-a194-5c0234d95298" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_01a15aa3-1087-7623-b946-bc2b0475d99e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_01a15aa3-1087-7623-b946-bc2b0475d99e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_01a15aa3-1087-7623-b946-bc2b0475d99e" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_01a15aa3-1087-7623-b946-bc2b0475d99e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_01a15aa3-1087-7a3c-803d-99194c934f2a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_01a15aa3-1087-7623-b946-bc2b0475d99e" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_01a15aa3-1087-7a3c-803d-99194c934f2a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_XTIDroneHoldingsMember_01a15aa3-1087-7bbc-8f23-3b8473dd0e1a" xlink:href="xtia-20260630.xsd#xtia_XTIDroneHoldingsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_01a15aa3-1087-7a3c-803d-99194c934f2a" xlink:to="loc_xtia_XTIDroneHoldingsMember_01a15aa3-1087-7bbc-8f23-3b8473dd0e1a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_01a15aa3-1087-7f5f-a252-77eed45aaca7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_01a01532-1934-7706-a194-5c0234d95298" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_01a15aa3-1087-7f5f-a252-77eed45aaca7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_01a15aa3-1087-7f5f-a252-77eed45aaca7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_01a15aa3-1087-7f5f-a252-77eed45aaca7" xlink:to="loc_us-gaap_RelatedPartyDomain_01a15aa3-1087-7f5f-a252-77eed45aaca7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_01a15aa3-1087-71ca-a67c-7ab0f724b190" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_01a15aa3-1087-7f5f-a252-77eed45aaca7" xlink:to="loc_us-gaap_RelatedPartyDomain_01a15aa3-1087-71ca-a67c-7ab0f724b190" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyMember_01a15aa3-1087-7cff-a1f9-fc13c8106953" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_01a15aa3-1087-71ca-a67c-7ab0f724b190" xlink:to="loc_us-gaap_RelatedPartyMember_01a15aa3-1087-7cff-a1f9-fc13c8106953" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_01a15aa3-1087-7084-8071-6b53f3b79ab2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_01a01532-1934-7706-a194-5c0234d95298" xlink:to="loc_us-gaap_StatementClassOfStockAxis_01a15aa3-1087-7084-8071-6b53f3b79ab2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_01a15aa3-1087-7084-8071-6b53f3b79ab2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_01a15aa3-1087-7084-8071-6b53f3b79ab2" xlink:to="loc_us-gaap_ClassOfStockDomain_01a15aa3-1087-7084-8071-6b53f3b79ab2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_01a15aa3-1087-7d35-bbba-2c8106f6c75a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_01a15aa3-1087-7084-8071-6b53f3b79ab2" xlink:to="loc_us-gaap_ClassOfStockDomain_01a15aa3-1087-7d35-bbba-2c8106f6c75a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_NoncontrollingInterestClassBUnitsMember_01a15aa3-1087-759e-8d83-244835431339" xlink:href="xtia-20260630.xsd#xtia_NoncontrollingInterestClassBUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_01a15aa3-1087-7d35-bbba-2c8106f6c75a" xlink:to="loc_xtia_NoncontrollingInterestClassBUnitsMember_01a15aa3-1087-759e-8d83-244835431339" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_ClassBUnitsMember_01a15aa3-1087-7195-a3a5-877e9eb1e524" xlink:href="xtia-20260630.xsd#xtia_ClassBUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockDomain_01a15aa3-1087-7d35-bbba-2c8106f6c75a" xlink:to="loc_xtia_ClassBUnitsMember_01a15aa3-1087-7195-a3a5-877e9eb1e524" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_01a15aa3-1087-70dc-bbb1-8d1c2915bde1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_01a01532-1934-7706-a194-5c0234d95298" xlink:to="loc_us-gaap_DebtInstrumentAxis_01a15aa3-1087-70dc-bbb1-8d1c2915bde1" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_01a15aa3-1087-70dc-bbb1-8d1c2915bde1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_01a15aa3-1087-70dc-bbb1-8d1c2915bde1" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_01a15aa3-1087-70dc-bbb1-8d1c2915bde1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_01a15aa3-1087-7882-a58b-0cdd6a706829" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_01a15aa3-1087-70dc-bbb1-8d1c2915bde1" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_01a15aa3-1087-7882-a58b-0cdd6a706829" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_AcquisitionRelatedPromissoryNotesMember_01a15aa3-1087-7224-b64b-daad97b96e56" xlink:href="xtia-20260630.xsd#xtia_AcquisitionRelatedPromissoryNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_01a15aa3-1087-7882-a58b-0cdd6a706829" xlink:to="loc_xtia_AcquisitionRelatedPromissoryNotesMember_01a15aa3-1087-7224-b64b-daad97b96e56" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued_01a1542d-9fb7-7545-85c5-906eb82e1c7f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_01a1542d-9fb7-703b-a71f-dd0ac344cf00" xlink:to="loc_us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued_01a1542d-9fb7-7545-85c5-906eb82e1c7f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityOwnershipPercentageExcludingConsolidatedEntityAndEquityMethodInvestee_01a1542d-9fb7-7391-89d5-dfd77b75d757" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityOwnershipPercentageExcludingConsolidatedEntityAndEquityMethodInvestee"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_01a1542d-9fb7-703b-a71f-dd0ac344cf00" xlink:to="loc_us-gaap_EquityOwnershipPercentageExcludingConsolidatedEntityAndEquityMethodInvestee_01a1542d-9fb7-7391-89d5-dfd77b75d757" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRepaidPrincipal_01a1542d-9fb7-7997-9d87-8e34d67af7d8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentRepaidPrincipal"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_01a1542d-9fb7-703b-a71f-dd0ac344cf00" xlink:to="loc_us-gaap_DebtInstrumentRepaidPrincipal_01a1542d-9fb7-7997-9d87-8e34d67af7d8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpense_01a1542d-9fb7-7eee-a10b-630f9f289c8f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_01a1542d-9fb7-703b-a71f-dd0ac344cf00" xlink:to="loc_us-gaap_InterestExpense_01a1542d-9fb7-7eee-a10b-630f9f289c8f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtNoncurrent_01a1542d-9fb7-799a-ab2a-0bd1d54a9e28" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermDebtNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_01a1542d-9fb7-703b-a71f-dd0ac344cf00" xlink:to="loc_us-gaap_LongTermDebtNoncurrent_01a1542d-9fb7-799a-ab2a-0bd1d54a9e28" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.xtiaircraft.com/role/DiscontinuedOperationsNarrativeDetails" xlink:type="simple" xlink:href="xtia-20260630.xsd#DiscontinuedOperationsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.xtiaircraft.com/role/DiscontinuedOperationsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019f660f-6aa0-7b9d-9bd4-9a56186f2c64" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_DiscontinuedOperationsDetailsTable_019f660f-6aa0-7f0c-90b1-2b8df6a5c184" xlink:href="xtia-20260630.xsd#xtia_DiscontinuedOperationsDetailsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019f660f-6aa0-7b9d-9bd4-9a56186f2c64" xlink:to="loc_xtia_DiscontinuedOperationsDetailsTable_019f660f-6aa0-7f0c-90b1-2b8df6a5c184" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019f660f-6aa0-7e0c-8bb6-49277dcb5324" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_xtia_DiscontinuedOperationsDetailsTable_019f660f-6aa0-7f0c-90b1-2b8df6a5c184" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019f660f-6aa0-7e0c-8bb6-49277dcb5324" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_019f660f-6aa0-7e0c-8bb6-49277dcb5324_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019f660f-6aa0-7e0c-8bb6-49277dcb5324" xlink:to="loc_us-gaap_RelatedPartyDomain_019f660f-6aa0-7e0c-8bb6-49277dcb5324_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_019f660f-6aa0-7360-ac07-3bf96837d6ba" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019f660f-6aa0-7e0c-8bb6-49277dcb5324" xlink:to="loc_us-gaap_RelatedPartyDomain_019f660f-6aa0-7360-ac07-3bf96837d6ba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_InpixonMember_019f660f-6aa0-7765-b37e-388f96b0019c" xlink:href="xtia-20260630.xsd#xtia_InpixonMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_019f660f-6aa0-7360-ac07-3bf96837d6ba" xlink:to="loc_xtia_InpixonMember_019f660f-6aa0-7765-b37e-388f96b0019c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationAxis_01a1318c-d9a2-79f9-957b-b71f44fb1f43" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupClassificationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_xtia_DiscontinuedOperationsDetailsTable_019f660f-6aa0-7f0c-90b1-2b8df6a5c184" xlink:to="loc_us-gaap_DisposalGroupClassificationAxis_01a1318c-d9a2-79f9-957b-b71f44fb1f43" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_01a1318c-d9a2-79f9-957b-b71f44fb1f43_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_01a1318c-d9a2-79f9-957b-b71f44fb1f43" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_01a1318c-d9a2-79f9-957b-b71f44fb1f43_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_01a1318c-d9a2-72e6-9561-366cddbb843f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_01a1318c-d9a2-79f9-957b-b71f44fb1f43" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_01a1318c-d9a2-72e6-9561-366cddbb843f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDiscontinuedOperationsMember_01a1318c-d9a2-7c3f-84b5-a87470b5bc7f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDiscontinuedOperationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_01a1318c-d9a2-72e6-9561-366cddbb843f" xlink:to="loc_us-gaap_SegmentDiscontinuedOperationsMember_01a1318c-d9a2-7c3f-84b5-a87470b5bc7f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockConsiderationReceivedOnTransaction_019f660f-6aa0-70a7-a90e-e54a8ad45315" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SaleOfStockConsiderationReceivedOnTransaction"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019f660f-6aa0-7b9d-9bd4-9a56186f2c64" xlink:to="loc_us-gaap_SaleOfStockConsiderationReceivedOnTransaction_019f660f-6aa0-70a7-a90e-e54a8ad45315" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NotesReceivableFairValueDisclosure_019f660f-6aa0-73ef-ac35-3da8c2505f9d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NotesReceivableFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019f660f-6aa0-7b9d-9bd4-9a56186f2c64" xlink:to="loc_us-gaap_NotesReceivableFairValueDisclosure_019f660f-6aa0-73ef-ac35-3da8c2505f9d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_NoteReceivableAccruedInterestRate_019f660f-6aa0-7dbe-a94d-95b5b33f5b1a" xlink:href="xtia-20260630.xsd#xtia_NoteReceivableAccruedInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019f660f-6aa0-7b9d-9bd4-9a56186f2c64" xlink:to="loc_xtia_NoteReceivableAccruedInterestRate_019f660f-6aa0-7dbe-a94d-95b5b33f5b1a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_NoteReceivableUnwindOptionPeriod_01a154c5-189d-7eca-9e07-1cc72b55e143" xlink:href="xtia-20260630.xsd#xtia_NoteReceivableUnwindOptionPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019f660f-6aa0-7b9d-9bd4-9a56186f2c64" xlink:to="loc_xtia_NoteReceivableUnwindOptionPeriod_01a154c5-189d-7eca-9e07-1cc72b55e143" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_EstimateFairValueOfPurchaseAmount_019f660f-6aa0-75b9-aa58-34f9106c1139" xlink:href="xtia-20260630.xsd#xtia_EstimateFairValueOfPurchaseAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019f660f-6aa0-7b9d-9bd4-9a56186f2c64" xlink:to="loc_xtia_EstimateFairValueOfPurchaseAmount_019f660f-6aa0-75b9-aa58-34f9106c1139" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_LossOnDisposal_019f660f-6aa0-7945-a47e-2d6f9103b426" xlink:href="xtia-20260630.xsd#xtia_LossOnDisposal"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019f660f-6aa0-7b9d-9bd4-9a56186f2c64" xlink:to="loc_xtia_LossOnDisposal_019f660f-6aa0-7945-a47e-2d6f9103b426" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax_01a1318c-d9a2-79e8-9184-d3f5444d9e84" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019f660f-6aa0-7b9d-9bd4-9a56186f2c64" xlink:to="loc_us-gaap_DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax_01a1318c-d9a2-79e8-9184-d3f5444d9e84" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableAndOtherAccruedLiabilitiesCurrent_01a1318c-d9a2-7856-8e11-d250dd9a0350" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccountsPayableAndOtherAccruedLiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019f660f-6aa0-7b9d-9bd4-9a56186f2c64" xlink:to="loc_us-gaap_AccountsPayableAndOtherAccruedLiabilitiesCurrent_01a1318c-d9a2-7856-8e11-d250dd9a0350" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_01a1318c-d9a2-7378-8654-871629f647dd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PrepaidExpenseAndOtherAssetsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019f660f-6aa0-7b9d-9bd4-9a56186f2c64" xlink:to="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_01a1318c-d9a2-7378-8654-871629f647dd" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxAdjustmentsSettlementsAndUnusualProvisions_019f660f-6aa0-773a-9160-6d8bd3e3c270" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TaxAdjustmentsSettlementsAndUnusualProvisions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019f660f-6aa0-7b9d-9bd4-9a56186f2c64" xlink:to="loc_us-gaap_TaxAdjustmentsSettlementsAndUnusualProvisions_019f660f-6aa0-773a-9160-6d8bd3e3c270" xlink:type="arc" order="9"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.xtiaircraft.com/role/DiscontinuedOperationsScheduleofDisposalDetails" xlink:type="simple" xlink:href="xtia-20260630.xsd#DiscontinuedOperationsScheduleofDisposalDetails"/>
  <link:definitionLink xlink:role="http://www.xtiaircraft.com/role/DiscontinuedOperationsScheduleofDisposalDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019f660f-6aa0-7859-8b70-d013cf38ec81" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_019f660f-6aa0-75bd-a7a2-e886b6de5580" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019f660f-6aa0-7859-8b70-d013cf38ec81" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_019f660f-6aa0-75bd-a7a2-e886b6de5580" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationAxis_019f660f-6aa0-75df-9e14-4770c077866b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupClassificationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_019f660f-6aa0-75bd-a7a2-e886b6de5580" xlink:to="loc_us-gaap_DisposalGroupClassificationAxis_019f660f-6aa0-75df-9e14-4770c077866b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_019f660f-6aa0-75df-9e14-4770c077866b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_019f660f-6aa0-75df-9e14-4770c077866b" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_019f660f-6aa0-75df-9e14-4770c077866b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_019f660f-6aa0-7309-93d4-5780d661085a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_019f660f-6aa0-75df-9e14-4770c077866b" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_019f660f-6aa0-7309-93d4-5780d661085a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDiscontinuedOperationsMember_019f660f-6aa0-7276-9048-c38f7cc2a82c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDiscontinuedOperationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_019f660f-6aa0-7309-93d4-5780d661085a" xlink:to="loc_us-gaap_SegmentDiscontinuedOperationsMember_019f660f-6aa0-7276-9048-c38f7cc2a82c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationRevenue_019f660f-6aa0-7e88-ae59-d837b552f340" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019f660f-6aa0-7859-8b70-d013cf38ec81" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationRevenue_019f660f-6aa0-7e88-ae59-d837b552f340" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationCostsOfGoodsSold_019f660f-6aa0-7fd4-b420-b534f29e2225" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationCostsOfGoodsSold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019f660f-6aa0-7859-8b70-d013cf38ec81" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationCostsOfGoodsSold_019f660f-6aa0-7fd4-b420-b534f29e2225" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_DisposalGroupIncludingDiscontinuedOperationResearchAndDevelopment_019f660f-6aa0-79f9-8819-38d279e8d9a8" xlink:href="xtia-20260630.xsd#xtia_DisposalGroupIncludingDiscontinuedOperationResearchAndDevelopment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019f660f-6aa0-7859-8b70-d013cf38ec81" xlink:to="loc_xtia_DisposalGroupIncludingDiscontinuedOperationResearchAndDevelopment_019f660f-6aa0-79f9-8819-38d279e8d9a8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_DisposalGroupIncludingDiscontinuedOperationSalesAndMarketing_019f660f-6aa0-7f04-a48b-1704f5c92e87" xlink:href="xtia-20260630.xsd#xtia_DisposalGroupIncludingDiscontinuedOperationSalesAndMarketing"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019f660f-6aa0-7859-8b70-d013cf38ec81" xlink:to="loc_xtia_DisposalGroupIncludingDiscontinuedOperationSalesAndMarketing_019f660f-6aa0-7f04-a48b-1704f5c92e87" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationGeneralAndAdministrativeExpense_019f660f-6aa0-7632-baa2-9a954b56c7c7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationGeneralAndAdministrativeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019f660f-6aa0-7859-8b70-d013cf38ec81" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationGeneralAndAdministrativeExpense_019f660f-6aa0-7632-baa2-9a954b56c7c7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_DisposalGroupIncludingDiscontinuedOperationImpairmentOfGoodwillAndIntangibleAssets_019f660f-6aa0-781f-afb5-e38d26b5337b" xlink:href="xtia-20260630.xsd#xtia_DisposalGroupIncludingDiscontinuedOperationImpairmentOfGoodwillAndIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019f660f-6aa0-7859-8b70-d013cf38ec81" xlink:to="loc_xtia_DisposalGroupIncludingDiscontinuedOperationImpairmentOfGoodwillAndIntangibleAssets_019f660f-6aa0-781f-afb5-e38d26b5337b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_DisposalGroupIncludingDiscontinuedOperationOtherIncomeExpenseNet_019f660f-6aa0-7b8b-8aff-6285b62467c6" xlink:href="xtia-20260630.xsd#xtia_DisposalGroupIncludingDiscontinuedOperationOtherIncomeExpenseNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019f660f-6aa0-7859-8b70-d013cf38ec81" xlink:to="loc_xtia_DisposalGroupIncludingDiscontinuedOperationOtherIncomeExpenseNet_019f660f-6aa0-7b8b-8aff-6285b62467c6" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_DisposalGroupIncludingDiscontinuedOperationNetLossBeforeTax_019f660f-6aa0-71d4-9db5-cd385613ab7a" xlink:href="xtia-20260630.xsd#xtia_DisposalGroupIncludingDiscontinuedOperationNetLossBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019f660f-6aa0-7859-8b70-d013cf38ec81" xlink:to="loc_xtia_DisposalGroupIncludingDiscontinuedOperationNetLossBeforeTax_019f660f-6aa0-71d4-9db5-cd385613ab7a" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_DisposalGroupIncludingDiscontinuedOperationIncomeTaxProvision_019f660f-6aa0-71a3-80aa-44b5bcc22dd5" xlink:href="xtia-20260630.xsd#xtia_DisposalGroupIncludingDiscontinuedOperationIncomeTaxProvision"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019f660f-6aa0-7859-8b70-d013cf38ec81" xlink:to="loc_xtia_DisposalGroupIncludingDiscontinuedOperationIncomeTaxProvision_019f660f-6aa0-71a3-80aa-44b5bcc22dd5" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax_019f660f-6aa0-7b69-99c9-be6f8321ee23" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019f660f-6aa0-7859-8b70-d013cf38ec81" xlink:to="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax_019f660f-6aa0-7b69-99c9-be6f8321ee23" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax_019f660f-6aa0-7239-a7da-579a7a3fcb75" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019f660f-6aa0-7859-8b70-d013cf38ec81" xlink:to="loc_us-gaap_DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax_019f660f-6aa0-7239-a7da-579a7a3fcb75" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity_019f660f-6aa0-7273-8533-04ca1440fc36" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019f660f-6aa0-7859-8b70-d013cf38ec81" xlink:to="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity_019f660f-6aa0-7273-8533-04ca1440fc36" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasicAbstract_019f660f-6aa0-7d26-9319-fd7355e6962b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EarningsPerShareBasicAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019f660f-6aa0-7859-8b70-d013cf38ec81" xlink:to="loc_us-gaap_EarningsPerShareBasicAbstract_019f660f-6aa0-7d26-9319-fd7355e6962b" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare_019f660f-6aa0-7b20-a9b6-ae0f640eaaac" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicAbstract_019f660f-6aa0-7d26-9319-fd7355e6962b" xlink:to="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare_019f660f-6aa0-7b20-a9b6-ae0f640eaaac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare_019fcddb-dd31-797b-acf0-bb63898aaa8e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicAbstract_019f660f-6aa0-7d26-9319-fd7355e6962b" xlink:to="loc_us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare_019fcddb-dd31-797b-acf0-bb63898aaa8e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_LossOnSaleOfDiscontinuedComponent_019f660f-6aa0-7dee-be58-47ccbe34b49a" xlink:href="xtia-20260630.xsd#xtia_LossOnSaleOfDiscontinuedComponent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicAbstract_019f660f-6aa0-7d26-9319-fd7355e6962b" xlink:to="loc_xtia_LossOnSaleOfDiscontinuedComponent_019f660f-6aa0-7dee-be58-47ccbe34b49a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_TotalDiscontinuedOperations_019f660f-6aa0-727c-bad9-5b1b8396fe79" xlink:href="xtia-20260630.xsd#xtia_TotalDiscontinuedOperations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicAbstract_019f660f-6aa0-7d26-9319-fd7355e6962b" xlink:to="loc_xtia_TotalDiscontinuedOperations_019f660f-6aa0-727c-bad9-5b1b8396fe79" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_019f660f-6aa0-705f-84fb-426cd2321bf1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019f660f-6aa0-7859-8b70-d013cf38ec81" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_019f660f-6aa0-705f-84fb-426cd2321bf1" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_019f85bb-c342-7f1e-a869-afba124d24ee" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019f660f-6aa0-7859-8b70-d013cf38ec81" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_019f85bb-c342-7f1e-a869-afba124d24ee" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashProvidedByUsedInOperatingActivitiesDiscontinuedOperations_019f85bd-accc-700e-a124-b674dd3b3204" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashProvidedByUsedInOperatingActivitiesDiscontinuedOperations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019f660f-6aa0-7859-8b70-d013cf38ec81" xlink:to="loc_us-gaap_CashProvidedByUsedInOperatingActivitiesDiscontinuedOperations_019f85bd-accc-700e-a124-b674dd3b3204" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashProvidedByUsedInInvestingActivitiesDiscontinuedOperations_019f660f-6aa0-7ad5-86f6-ec5817edf413" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashProvidedByUsedInInvestingActivitiesDiscontinuedOperations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019f660f-6aa0-7859-8b70-d013cf38ec81" xlink:to="loc_us-gaap_CashProvidedByUsedInInvestingActivitiesDiscontinuedOperations_019f660f-6aa0-7ad5-86f6-ec5817edf413" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashProvidedByUsedInFinancingActivitiesDiscontinuedOperations_019f660f-6aa0-7bbb-812f-5011c751c962" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashProvidedByUsedInFinancingActivitiesDiscontinuedOperations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019f660f-6aa0-7859-8b70-d013cf38ec81" xlink:to="loc_us-gaap_CashProvidedByUsedInFinancingActivitiesDiscontinuedOperations_019f660f-6aa0-7bbb-812f-5011c751c962" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInDiscontinuedOperations_019f660f-6aa0-72ad-be0b-d06a01181359" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetCashProvidedByUsedInDiscontinuedOperations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_019f660f-6aa0-7859-8b70-d013cf38ec81" xlink:to="loc_us-gaap_NetCashProvidedByUsedInDiscontinuedOperations_019f660f-6aa0-72ad-be0b-d06a01181359" xlink:type="arc" order="18"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.xtiaircraft.com/role/SubsequentEventsDetails" xlink:type="simple" xlink:href="xtia-20260630.xsd#SubsequentEventsDetails"/>
  <link:definitionLink xlink:role="http://www.xtiaircraft.com/role/SubsequentEventsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventLineItems_01a01fb3-d215-7a05-8764-32d154b33b66" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTable_01a01fb3-d215-7bf6-8b91-30162d9829c3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SubsequentEventLineItems_01a01fb3-d215-7a05-8764-32d154b33b66" xlink:to="loc_us-gaap_SubsequentEventTable_01a01fb3-d215-7bf6-8b91-30162d9829c3" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_01a01fb3-d215-717b-a142-f35dc5e1ac6b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_01a01fb3-d215-7bf6-8b91-30162d9829c3" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_01a01fb3-d215-717b-a142-f35dc5e1ac6b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_01a01fb3-d215-717b-a142-f35dc5e1ac6b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_01a01fb3-d215-717b-a142-f35dc5e1ac6b" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_01a01fb3-d215-717b-a142-f35dc5e1ac6b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_01a01fb3-d215-762d-a397-26f97243502d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_01a01fb3-d215-717b-a142-f35dc5e1ac6b" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_01a01fb3-d215-762d-a397-26f97243502d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_01a01fb4-4d50-70a6-abf1-12b50c81fbce" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_01a01fb3-d215-762d-a397-26f97243502d" xlink:to="loc_us-gaap_SubsequentEventMember_01a01fb4-4d50-70a6-abf1-12b50c81fbce" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_01a15aa8-c429-7385-b3bf-533dd4f1a990" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_01a01fb3-d215-7bf6-8b91-30162d9829c3" xlink:to="loc_us-gaap_DebtInstrumentAxis_01a15aa8-c429-7385-b3bf-533dd4f1a990" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_01a15aa8-c429-7385-b3bf-533dd4f1a990_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_01a15aa8-c429-7385-b3bf-533dd4f1a990" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_01a15aa8-c429-7385-b3bf-533dd4f1a990_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_01a15aa8-c429-7a39-a369-2212511af7c2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_01a15aa8-c429-7385-b3bf-533dd4f1a990" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_01a15aa8-c429-7a39-a369-2212511af7c2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_AcquisitionRelatedPromissoryNotesMember_01a15aa8-c429-7c1e-956a-1b4248e1fe07" xlink:href="xtia-20260630.xsd#xtia_AcquisitionRelatedPromissoryNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_01a15aa8-c429-7a39-a369-2212511af7c2" xlink:to="loc_xtia_AcquisitionRelatedPromissoryNotesMember_01a15aa8-c429-7c1e-956a-1b4248e1fe07" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_AssetBasedRevolvingLineOfCreditDroneNerdsMember_01a15aa8-c429-704d-abdd-3fd779e26986" xlink:href="xtia-20260630.xsd#xtia_AssetBasedRevolvingLineOfCreditDroneNerdsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_01a15aa8-c429-7a39-a369-2212511af7c2" xlink:to="loc_xtia_AssetBasedRevolvingLineOfCreditDroneNerdsMember_01a15aa8-c429-704d-abdd-3fd779e26986" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_01a15aa8-c429-764d-9c4f-d3ca87fdf9bd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_01a01fb3-d215-7bf6-8b91-30162d9829c3" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_01a15aa8-c429-764d-9c4f-d3ca87fdf9bd" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_01a15aa8-c429-764d-9c4f-d3ca87fdf9bd_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_01a15aa8-c429-764d-9c4f-d3ca87fdf9bd" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_01a15aa8-c429-764d-9c4f-d3ca87fdf9bd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_01a15aa8-c429-73bc-855c-00ea0828193c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_01a15aa8-c429-764d-9c4f-d3ca87fdf9bd" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_01a15aa8-c429-73bc-855c-00ea0828193c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_DroneNerdsMember_01a15aa8-c429-7903-ab31-4055beb25a01" xlink:href="xtia-20260630.xsd#xtia_DroneNerdsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_01a15aa8-c429-73bc-855c-00ea0828193c" xlink:to="loc_xtia_DroneNerdsMember_01a15aa8-c429-7903-ab31-4055beb25a01" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_01a15aa8-c429-7bb8-8487-838b2b3e8dbc" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_01a01fb3-d215-7bf6-8b91-30162d9829c3" xlink:to="loc_srt_CounterpartyNameAxis_01a15aa8-c429-7bb8-8487-838b2b3e8dbc" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_01a15aa8-c429-7bb8-8487-838b2b3e8dbc_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_01a15aa8-c429-7bb8-8487-838b2b3e8dbc" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_01a15aa8-c429-7bb8-8487-838b2b3e8dbc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_01a15aa8-c429-7653-b127-9dc690ae9655" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_01a15aa8-c429-7bb8-8487-838b2b3e8dbc" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_01a15aa8-c429-7653-b127-9dc690ae9655" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_ValkryieSciencesHoldingsLLCMember_01a15aa8-c429-72bf-b10d-8f1600111182" xlink:href="xtia-20260630.xsd#xtia_ValkryieSciencesHoldingsLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_01a15aa8-c429-7653-b127-9dc690ae9655" xlink:to="loc_xtia_ValkryieSciencesHoldingsLLCMember_01a15aa8-c429-72bf-b10d-8f1600111182" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_DebtInstrumentScheduledPaymentNotRemitted_01a15aa8-c429-7770-a523-10c81138b73c" xlink:href="xtia-20260630.xsd#xtia_DebtInstrumentScheduledPaymentNotRemitted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_01a01fb3-d215-7a05-8764-32d154b33b66" xlink:to="loc_xtia_DebtInstrumentScheduledPaymentNotRemitted_01a15aa8-c429-7770-a523-10c81138b73c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtDefaultLongtermDebtAmount_01a15aa8-c429-789c-94a2-275aca517c39" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtDefaultLongtermDebtAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_01a01fb3-d215-7a05-8764-32d154b33b66" xlink:to="loc_us-gaap_DebtDefaultLongtermDebtAmount_01a15aa8-c429-789c-94a2-275aca517c39" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_01a15aa8-c429-72a3-8ad0-355133c61857" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_01a01fb3-d215-7a05-8764-32d154b33b66" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_01a15aa8-c429-72a3-8ad0-355133c61857" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_DebtInstrumentDefaultInterestRate_01a15aa9-c85f-7387-a044-09ca8a0bf78b" xlink:href="xtia-20260630.xsd#xtia_DebtInstrumentDefaultInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_01a01fb3-d215-7a05-8764-32d154b33b66" xlink:to="loc_xtia_DebtInstrumentDefaultInterestRate_01a15aa9-c85f-7387-a044-09ca8a0bf78b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_TariffRefundsRemittedToFormerOwners_01a15aa8-c429-71ec-bf7d-4bba8fbe47b9" xlink:href="xtia-20260630.xsd#xtia_TariffRefundsRemittedToFormerOwners"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_01a01fb3-d215-7a05-8764-32d154b33b66" xlink:to="loc_xtia_TariffRefundsRemittedToFormerOwners_01a15aa8-c429-71ec-bf7d-4bba8fbe47b9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_PromissoryNoteReceivableSoldToThirdParty_01a15aa8-c429-7c03-8133-be78f7968a21" xlink:href="xtia-20260630.xsd#xtia_PromissoryNoteReceivableSoldToThirdParty"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_01a01fb3-d215-7a05-8764-32d154b33b66" xlink:to="loc_xtia_PromissoryNoteReceivableSoldToThirdParty_01a15aa8-c429-7c03-8133-be78f7968a21" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_PromissoryNoteReceivable_01a15aa8-c429-7c7d-ad56-d1093faa30f6" xlink:href="xtia-20260630.xsd#xtia_PromissoryNoteReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_01a01fb3-d215-7a05-8764-32d154b33b66" xlink:to="loc_xtia_PromissoryNoteReceivable_01a15aa8-c429-7c7d-ad56-d1093faa30f6" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_xtia_PromissoryNoteReceivableAccruedInterestForgiven_01a15aa8-c429-748f-8cd0-9e085fe7c628" xlink:href="xtia-20260630.xsd#xtia_PromissoryNoteReceivableAccruedInterestForgiven"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_01a01fb3-d215-7a05-8764-32d154b33b66" xlink:to="loc_xtia_PromissoryNoteReceivableAccruedInterestForgiven_01a15aa8-c429-748f-8cd0-9e085fe7c628" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestReceivable_01a15aa8-c429-7d1a-bbc0-a9942ab997ac" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_01a01fb3-d215-7a05-8764-32d154b33b66" xlink:to="loc_us-gaap_InterestReceivable_01a15aa8-c429-7d1a-bbc0-a9942ab997ac" xlink:type="arc" order="8"/>
  </link:definitionLink>
</link:linkbase>
