A spar used in ships to extend the heads of fore-and-aft sails which are not set on stays. The foremost end of the gaff is termed the jaw, the outer part is called the peak. The jaw forms a semicircle, and is secured in its position by a jaw-rope passing round the mast; on it are strung several small wooden balls called trucks, to lessen the friction on the mast when the sail is hoisting or lowering.