1. a sailing vessel with a single mast set about one third of the boat's length aft of the bow;
The Collaborative International Dictionary of English v.0.48:
Sloop \Sloop\, n.[D. sloep, of uncertain origin. Cf. Shallop.]
1. (Naut.) A vessel having one mast and fore-and-aft rig,
consisting of a boom-and-gaff mainsail, jibs, staysail,
and gaff topsail. The typical sloop has a fixed bowsprit,
topmast, and standing rigging, while those of a cutter are
capable of being readily shifted. The sloop usually
carries a centerboard, and depends for stability upon
breadth of beam rather than depth of keel. The two types
have rapidly approximated since 1880. One radical
distinction is that a sloop may carry a centerboard. See
Cutter, and Illustration in Appendix.
2. (Naut.) In modern usage, a sailing vessel having one mast,
commonly with a Bermuda rig, with either a center-board or
a keel. In the United States, a sloop may have one or two
headsails, while in Western Europe and Great Britain a
sloop has only one headsail.
Sloop of war, formerly, a vessel of war rigged either as a
ship, brig, or schooner, and mounting from ten to
thirty-two guns; now, any war vessel larger than a
gunboat, and carrying guns on one deck only.
WordNet (r) 3.0 (2006):
n 1: a sailing vessel with a single mast set about one third of
the boat's length aft of the bow
The Free On-line Dictionary of Computing (30 December 2018):
"Parallel Programming in a Virtual Object Space", S. Lucco,
SIGPLAN Notices 22(12):26-34 (OOPSLA '87) (Dec 1987).