'tank-defeating' originates from modern English as a compound of 'tank' and 'defeat', where 'tank' referred to an armoured fighting vehicle and 'defeat' meant 'to overcome'.

'tank' was coined in early 20th century English (WWI) as a code name for the new armoured vehicles and entered common use as 'tank'; 'defeat' comes from Old French 'desfait'/'defait' (past participle of 'desfaire') ultimately from Latin components such as 'dis-' + 'facere'. These elements combined in modern English to form descriptive compounds like 'tank-defeating'.

The component 'defeat' originally carried senses like 'undo' or 'overcome' in Old French/Late Latin contexts; over time it took on the more focused sense 'to beat or destroy in battle', and in the 20th century the compound 'tank-defeating' came to mean specifically 'able to destroy or neutralize tanks'.