inconstant vs sexual activity

inconstant is not a noun while sexual activity is a noun.

Word	Noun	Adjective	Verb	Adverb
inconstant	No	Yes	No	No
sexual activity	Yes	No	No	No

inconstant (noun)	sexual activity (noun)
	activities associated with sexual intercourse

inconstant (adjective)	sexual activity (adjective)
likely to change frequently often without apparent or cogent reason; variable