sadness vs gloominess

sadness and gloominess both are nouns.

Word	Noun	Adjective	Verb	Adverb
sadness	Yes	No	No	No
gloominess	Yes	No	No	No

As nouns, sadness and gloominess are synonyms defined as:

sadness and gloominess: the quality of excessive mournfulness and uncheerfulness

Other synonyms of sadness include lugubriousness.

sadness (noun)	gloominess (noun)
the quality of excessive mournfulness and uncheerfulness	the quality of excessive mournfulness and uncheerfulness
emotions experienced when not in a state of well-being	The property of having a frowning or scowling appearance.
the state of being sad	a feeling of melancholy apprehension
	an atmosphere of depression and melancholy