an area of canvas or other fabric extended to the wind in such a way as to transmit the force of the wind to an assemblage of spars and rigging mounted firmly on a hull, raft, iceboat, etc., so as to drive it along.
2.
some similar piece or apparatus, as the part of an arm that catches the wind on a windmill.
3.
a voyage or excursion, especially in a sailing vessel: They went for a sail around the island.
4.
a sailing vessel or ship.
5.
sailing vessels collectively: The fleet numbered 30 sail.
to set the sail or sails of a boat or increase the amount of sail already set.
b.
to set out on a voyage: Make sail for the Leeward Islands.
18.
set sail, to start a sea voyage: We set sail at midnight for Nantucket.
19.
trim one's sails, Informal. to cut expenses; economize: We're going to have to trim our sails if we stay in business.
20.
under sail, with sails set; in motion; sailing: It was good to be under sail in the brisk wind and under the warm sun.
Origin: before 900; (noun) Middle English sail(e), seille,Old English segl; cognate with German Segel,Old Norse segl; (v.) Middle English seillen, saylen,Old English siglan, seglian; cognate with Dutch zeilen,Old Norse sigla
O.E. segl, from P.Gmc. *seglom (cf. Swed. segel, O.N. segl, O.Fris. seil, Du. zeil, O.H.G. segal, Ger. Segel), of obscure origin with no known cognates outside Gmc. Ir. seol, Welsh hwyl "sail" are Gmc. loan-words. Sometimes referred to PIE root *sek- "to cut," as if meaning "a cut piece of cloth." The