sexual activity vs obscenely

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

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

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

sexual activity (adverb)	obscenely (adverb)
	in a lewd and obscene manner
	to an obscene degree