fallboard vs fall-board

fallboard and fall-board both are nouns.

Word	Noun	Adjective	Verb	Adverb
fallboard	Yes	No	No	No
fall-board	Yes	No	No	No

As nouns, fallboard and fall-board are synonyms defined as:

fallboard and fall-board: the hinged protective covering that protects the keyboard of a piano when it is not being played

fallboard (noun)	fall-board (noun)
the hinged protective covering that protects the keyboard of a piano when it is not being played	the hinged protective covering that protects the keyboard of a piano when it is not being played