Word Origin & History
harpoon
1613, from Fr. harpon, from O.Fr. harpon "cramp iron, clamp" (described as a mason's tool for fastening stones together), from harper "to grapple, grasp," possibly of Gmc. origin, or from L. harpa- "hook" (cf. harpagonem "grappling hook," from Gk. *harpagon, related to harpe "sickle"). Earlier harping-iron (1596). Sense and spelling perhaps infl. by Du. (cf. M.Du. harpoen) or Basque, the first whaling peoples, who usually accompanied Eng. sailors on their early expeditions.
[hahr-poon] 
) Military. a jet-powered, radar-guided U.S. Navy cruise missile with a high explosive warhead designed for use against surface ships and launchable from a surface vessel, submerged submarine, or aircraft.