—n. 1. a self-propelled, cigar-shaped missile containing explosives and often equipped with a homing device, launched from a submarine or other warship, for destroying surface vessels or other submarines.
2. any of various submarine explosive devices for destroying hostile ships, as a mine.
3. a cartridge of gunpowder, dynamite, or the like, exploded in an oil well to facilitate the extraction of oil from the well.
4. a detonating device fastened to the top of a rail so as to be exploded by the pressure of a locomotive or car, thus giving an audible signal to members of a train crew.
5. any of various other explosive devices, as a firework that consists of an explosive wrapped up with gravel in a piece of tissue paper and that detonates when thrown forcibly on the ground or against a hard surface.
6. Also called torpe'do fish". an electric ray, esp. Torpedo nobiliana, of the Atlantic Ocean.
7. an electric catfish, Malapterurus electricus, inhabiting waters of tropical central Africa and the Nile valley.
8. Informal.a hero sandwich.
9. Slang.a gangster hired as a murderer.
—v.t. 1. to attack, hit, damage, or destroy with torpedoes.
2. to explode a torpedo in (an oil well) to facilitate the extraction of oil.
3. to undermine, ruin, or destroy: He torpedoed our plans.
—v.i. to attack, damage, or sink a ship with torpedoes.