OPERATIVE

/ˈɒpəɹətɪv/ ► audio Scrabble 14 Words With Friends 16

Definition

noun a person secretly employed in espionage for a government. — synonyms: secret_agent, intelligence_officer, intelligence_agent
noun someone who can be employed as a detective to collect information. — synonyms: private_detective, PI, private_eye, private_investigator, shamus, sherlock
adjective being in force or having or exerting force.
adjective relating to or requiring or amenable to treatment by surgery especially as opposed to medicine. — synonyms: surgical
adjective effective.
adjective (of e.g. a machine) performing or capable of performing. — synonyms: running(a), functional, working(a)

“He's usually in a good mood — the operative word there being "usually". Today was a disaster.”
“an operative motive”
“an operative dose, rule, or penalty”