Topsail

n.
  1. In a square-rigged vessel, the sail next above the lowermost sail on a mast. This sail is the one most frequently reefed or furled in working the ship. In a fore-and-aft rigged vessel, the sail set upon and above the gaff. See Cutter, Schooner, Sail, and Ship.
    2. Topsail schooner . (Naut.)
    See Schooner, and Illustration in Appendix.