lateen

latinalaispurjeella varustettu

latinalaispurje puhekieltä 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.
1980: The lateen sail is triangular or a quadrilateral which is almost triangular, the former being the type used by the Byzantines. — Richard W. Unger, The Ship in the Medieval Economy 600-1600, page 47.