Noun

• S: (n) secret agent, intelligence officer, intelligence agent, operative (a person secretly employed in espionage for a government)
• S: (n) private detective, PI, private eye, private investigator, operative, shamus, sherlock (someone who can be employed as a detective to collect information)

Adjective

• S: (adj) operative (being in force or having or exerting force) "operative regulations"; "the major tendencies operative in the American political system"
• S: (adj) surgical, operative (relating to or requiring or amenable to treatment by surgery especially as opposed to medicine) "a surgical appendix"; "a surgical procedure"; "operative dentistry"
• S: (adj) operative (effective; producing a desired effect) "the operative word"
• S: (adj) running, operative, functional, working ((of e.g. a machine) performing or capable of performing) "in running (or working) order"; "a functional set of brakes"