A torpedo is a type of missile or bomb fired underwater. To torpedo is to attack with torpedoes.
Torpedoes are cigar-shaped projectiles that are used to attack other submarines or boats. The word torpedo comes from the name of a kind of electric ray that numbs you with its sting (torpediniformes). Torpedoes can also be used to attack a target on land. When a submarine fires torpedoes, they're torpedoing the target. Torpedoes explode upon impact, and they're very powerful weapons.