What does "lateen" mean?

Lateen: Of or pertaining to a peculiar rig used in the Mediterranean and adjacent waters, esp. on the northern coast of Africa. See below. Lateen sail. Etym: [F. voile latine a sail in the shape of a right- angled triangle; cf. It. & Sp. vela latina; properly Latin sail. See Latin.] (Naut.) A triangular sail, extended by a long yard, which is slung at about one fourth of its length from the lower end, to a low mast, this end being brought down at the tack, while the other end is elevated at an angle or about forty-five degrees; -- used in small boats, feluccas, xebecs, etc., especially in the Mediterranean and adjacent waters. Some lateen sails have also a boom on the lower side.