Har·poon n.  A spear or javelin used to strike and kill large fish, as whales; a harping iron.  It consists of a long shank, with a broad, flat, triangular head, sharpened at both edges, and is thrown by hand, or discharged from a gun.
 Harpoon fork, a kind of hayfork, consisting of a bar with hinged barbs at one end and a loop for a rope at the other end, used for lifting hay from the load by horse power.
 Harpoon gun, a gun used in the whale fishery for shooting the harpoon into a whale.