postoperative vs operative

postoperative is not a noun while operative is a noun.

Word	Noun	Adjective	Verb	Adverb
postoperative	No	Yes	No	No
operative	Yes	Yes	No	No

postoperative (noun)	operative (noun)
	someone who can be employed as a detective to collect information and assist in criminal investigations
	a person secretly employed in espionage for a government

postoperative (adjective)	operative (adjective)
happening or done after a surgical operation	being in force or having or exerting force
	relating to or requiring or amenable to treatment by surgery especially as opposed to medicine
	(of e.g. a machine) performing or capable of performing
	effective; producing a desired effect