Definition from Wiktionary, the free dictionary
foresail (plural foresails)
- (nautical, on a square-rigged ship) The lowest (and usually the largest) square sail hung on the foremast
- (nautical) A square fore-and-aft sail set on the foremast, but behind it, on a schooner or other similar vessel.
- (nautical, on a sloop) A triangular sail set forward of the foremast: forestaysail.
lowest square sail on foremast
square fore-and-aft sail set behind the foremast