cheerlessness vs uncheerfulness

cheerlessness and uncheerfulness both are nouns.

Word	Noun	Adjective	Verb	Adverb
cheerlessness	Yes	No	No	No
uncheerfulness	Yes	No	No	No

As nouns, cheerlessness and uncheerfulness are synonyms defined as:

cheerlessness and uncheerfulness: a feeling of dreary or pessimistic sadness

cheerlessness (noun)	uncheerfulness (noun)
a feeling of dreary or pessimistic sadness	not conducive to cheer or good spirits
	a feeling of dreary or pessimistic sadness