Source : Webster's Revised Unabridged Dictionary (1913)

Foresail \Fore"sail`\, n. (Naut.)
   (a) The sail bent to the foreyard of a square-rigged vessel,
       being the lowest sail on the foremast.
   (b) The gaff sail set on the foremast of a schooner.
   (c) The fore staysail of a sloop, being the triangular sail
       next forward of the mast.

Source : WordNet®

foresail
     n : the lowest sail on the foremast of a square-rigged vessel