lateen

noun

1. A triangular fore-and-aft sail set on a boom in such way that the tack is attached to the hull of the vessel and the free end of the boom lifts the sail.

   “The shape of the lateen sail is triangular, or precisely that of a large fore-sail; it requires a long tapering yard to spread it, which will slightly bow or bend towards the middle when a stiff breeze fills the sail; a boom is used for some lateen sails, but not for all.”

   “Not only is its supporting and controlling rigging best suited to that sail position but, even more important, the sail itself thus presents a rigid leading-edge: the mast, in the case of most modern sailboats, or the yardarm to which the sail is attached, in the case of the medieval Mediterranean lateen or the modern Sailfish. Fore-and-aft rigs come in a variety of shapes, but the medieval Mediterranean lateen was triangular, and this too was an asset.”

   “The lateen sail is triangular or a quadrilateral which is almost triangular, the former being the type used by the Byzantines.”