1) Big canvas 2) Canvas 3) Canvass 4) Important item on a schooner 5) Jib relative 6) Kin of a topgallant 7) Mast canvas 8) Part of a schooner 9) Part of a square-rigger 10) Primary canvas 11) Sail 12) Schooner feature 13) Sheet 14) Square-rigger need 15) What a sane male turns at sea 16) Windjammer sheet 
A mainsail is a sail located behind the main mast of a sailing vessel. On a square rigged vessel, it is the lowest and largest sail on the main mast. On a fore-and-aft rigged vessel, it is the lowest and largest and often the only sail rigged aft of the main mast, and is controlled along its foot by a spar known as the boom. A sail rigged in this ...
principal sail on a ship's mainmast
principal sail on a ship's mainmast
• (n.) The principal sail in a ship or other vessel.
The largest sail. (Except for the spinnaker.)
the largest sail of a dinghy
Main'sail` (mān'sāl`) noun (Nautical) The principal sail in a ship or other vessel. « [ They] hoised up the mainsail to the wind.» Acts xxvii. 40. » The mainsail of a ship is extended upon a yard attached to the mainmast, and that of a sloop...
The lowest square sail on the mainmast.
[n] - the lowermost sail on the mainmast
noun the lowermost sail on the mainmast
The sail behind the mast.