Webster's Revised Unabridged Dictionary · 1913

Gaff

Gaff (gaf) , noun

[Old English gaffe, French gaffe an iron hook with which seamen pull great fishes into their ships; compare Ir. gaf, gafa hook; perh. akin to German gabel fork, Sanskrit gabhasti. Compare Gaffle, Gable.]

1.
A barbed spear or a hook with a handle, used by fishermen in securing heavy fish.
2.
(Nautical) The spar upon which the upper edge of a fore-and-aft sail is extended.
3.
Same as Gaffle, 1. — Wright

Gaff , transitive verb

To strike with a gaff or barbed spear; to secure by means of a gaff; as, to gaff a salmon.