har·poon / ˌhärˈpoōn/ • n. a barbed spearlike missile attached to a long rope and thrown by hand or fired from a gun, used for catching whales and other large sea creatures.• v. [tr.] spear (something) with a harpoon.DERIVATIVES: har·poon·er n.ORIGIN: early 17th cent. (denoting a barbed dart or spear): from French harpon, from harpe ‘dog's claw, clamp,’ via Latin from Greek harpē ‘sickle.’

harpoon sb. XVII. — F. harpon, f. harpe dog's claw, cramp-iron, clamp — L. harpē, harpa — Gr. hárpē sickle.
Hence vb. XVIII.