sexual practice vs illicit

sexual practice is a noun but illicit is not a noun.

Word	Noun	Adjective	Verb	Adverb
sexual practice	Yes	No	No	No
illicit	No	Yes	No	No

sexual practice (noun)	illicit (noun)
activities associated with sexual intercourse

sexual practice (adjective)	illicit (adjective)
	contrary to accepted morality (especially sexual morality) or convention
	contrary to or forbidden by law