weather sheet vs mainsheet

weather sheet and mainsheet both are nouns.

Word	Noun	Adjective	Verb	Adverb
weather sheet	Yes	No	No	No
mainsheet	Yes	No	No	No

As nouns, weather sheet and mainsheet are synonyms defined as:

weather sheet and mainsheet: (nautical) a line (rope or chain) that regulates the angle at which a sail is set in relation to the wind

Other synonyms of weather sheet include sheet, shroud, tack.

weather sheet (noun)	mainsheet (noun)
(nautical) a line (rope or chain) that regulates the angle at which a sail is set in relation to the wind	(nautical) a line (rope or chain) that regulates the angle at which a sail is set in relation to the wind