cheerfulness vs cheer

cheerfulness and cheer both are nouns.

Word	Noun	Adjective	Verb	Adverb
cheerfulness	Yes	No	No	No
cheer	Yes	No	Yes	No

As nouns, cheerfulness and cheer are synonyms defined as:

cheerfulness and cheer: the quality of being cheerful and dispelling gloom

Other synonyms of cheerfulness include sunniness, sunshine.

cheerfulness (noun)	cheer (noun)
the quality of being cheerful and dispelling gloom	the quality of being cheerful and dispelling gloom
a feeling of spontaneous good spirits	a cry or shout of approval

cheerfulness (verb)	cheer (verb)
	become cheerful
	spur on or encourage especially by cheers and shouts
	show approval or good wishes by shouting
	cause (somebody) to feel happier or more cheerful
	give encouragement to