'torpedo-resistant' originates from modern English as a compound of the noun 'torpedo' and the adjective 'resistant'. 'Torpedo' (English) ultimately comes from Latin 'torpedō' (or 'torpidō'), where 'torpere' meant 'to be numb' and referred originally to the electric ray and later to an explosive naval weapon. 'Resistant' comes from Latin 'resistere', where 're-' meant 'back' or 'against' and 'sistere' (from 'stare') meant 'to stand (firm).'

The element 'torpedo' entered English in the 18th century from Latin 'torpedō' (originally referring to an electric ray and the numbness it caused) and was extended to mean an underwater explosive weapon in the 19th century; 'resistant' descends from Late Latin 'resistens' (present participle of 'resistere') and entered English via Old French/Latin. The compound 'torpedo-resistant' is a 20th-century English formation, becoming common in naval and technical descriptions from WWI and especially WWII onward.

Initially 'torpedo' referred to numbness and the electric ray, then shifted to denote an underwater explosive weapon; 'resistant' has retained the sense of 'standing against'. Combined, 'torpedo-resistant' has consistently meant 'capable of resisting torpedo attack', though it has also been used metaphorically in later usage.