Mainsail
Pronunciation : Main"sail`
Part of Speech : n.
Definition : Defn: The principal sail in a ship or other vessel. [They] hoised up the mainsail to the wind. Acts xxvii. 40.
Note: The mainsail of a ship is extended upon a yard attached to the mainmast, and that of a sloop or schooner upon the boom.
(Naut.)
Source : Webster's Unabridged Dictionary, 1913