obscene vs sexual activity

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

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

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

obscene (adjective)	sexual activity (adjective)
suggestive of or tending to moral looseness
designed to incite to indecency or lust
offensive to the mind