sexual activity vs unlawful

sexual activity is a noun but unlawful is not a noun.

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

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

sexual activity (adjective)	unlawful (adjective)
	contrary to or prohibited by or defiant of law
	contrary to or forbidden by law
	having no legally established claim
	not morally right or permissible
	not conforming to legality, moral law, or social convention