harpoon, barbed spear used to kill whales, tuna, swordfish, and other large sea creatures, formerly thrown by hand but now, in the case of whales, shot from especially constructed guns.
The hand-thrown harpoon has two sets of sharp barbs and is made in two parts, the lily iron, about 5 inches (13 centimetres) long, which contains the barbs, and a shaft about 18 in. long. The gun-projected harpoon explodes when it has struck the whale, expanding the barbs and killing the animal instantly.