the word torpedo entered english in the early 16th century, directly from latin 'torpedo', which meant 'numbness' or 'lethargy' and was also the name for the electric ray fish. this latin term derives from the verb 'torpere', meaning 'to be stiff or numb'. the connection to the weapon is metaphorical: just as the fish delivers a numbing electric shock, the naval weapon delivers a sudden, paralyzing blow to a ship. the modern sense of a self-propelled underwater missile was first recorded in the late 18th century, solidifying the link between the creature's stunning effect and the weapon's destructive purpose.

the word is a direct borrowing from latin and is not productively segmented into meaningful sub-parts in modern english.