means A self-propelled underwater missile launched from ships, submarines, or aircraft to strike and sink enemy vessels by detonating against their hulls.

from From Latin 'torpedo,' meaning 'numbness' or 'stiffness' (from 'torpere,' to be sluggish or stiff) — the same root that gives us 'torpid.' The word first named the electric ray, a flat fish that delivers a numbing jolt to anything that touches it. When inventors built a weapon that lurked unseen and delivered a sudden paralyzing shock to ships, the fish's name fit perfectly. Early 'torpedoes' were actually what we'd now call naval mines; the self-propelled version came later in the 19th century but kept the borrowed name.