In a square-rigged vessel, the sail next above the lowermostsail on a mast. This sail is the one most frequently reefed or furledin working the ship. In a fore-and-aft rigged vessel, the sail setupon and above the gaff. See Cutter, Schooner, Sail, and Ship.Topsail schooner. (Naut.) See Schooner, and