The Collaborative International Dictionary of English v.0.48:

lateen \la*teen"\, a.
   1. (Naut.) Of or pertaining to a peculiar rig used in the
      Mediterranean and adjacent waters, esp. on the northern
      coast of Africa; pertaining to a lateen sail. See below.
      [1913 Webster]

   2. rigged with a triangular (lateen sail).

   Syn: lateen-rigged.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

lateen
    adj 1: rigged with a triangular (lateen) sail [syn: lateen,
           lateen-rigged]
    n 1: a triangular fore-and-aft sail used especially in the
         Mediterranean [syn: lateen, lateen sail]