sexual practice vs improper

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

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

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

sexual practice (adjective)	improper (adjective)
	not suitable or right or appropriate
	not appropriate for a purpose or occasion
	not conforming to legality, moral law, or social convention