gregariousness vs ungregarious

gregariousness is a noun but ungregarious is not a noun.

Word	Noun	Adjective	Verb	Adverb
gregariousness	Yes	No	No	No
ungregarious	No	Yes	No	No

gregariousness (noun)	ungregarious (noun)
the quality of being gregarious--having a dislike of being alone

gregariousness (adjective)	ungregarious (adjective)
	(of animals) not gregarious
	(of plants) growing together in groups that are not close together
	not disposed to seek company