operative has 13 distinct synonyms spread across 4 of its 6 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. Its one recorded opposite is inoperative.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
being in force or having or exerting force
“operative regulations”
relating to or requiring or amenable to treatment by surgery especially as opposed to medicine
“a surgical appendix”
(of e.g. a machine) performing or capable of performing
“in running (or working) order”
a person secretly employed in espionage for a government
1 of the 6 recorded senses carries no synonym, antonym or related term, so it is not shown above. Every sense, with its definition and examples, is on the full entry for operative.
Synonyms, antonyms and the broader and narrower relations for operative come from Princeton University’s WordNet. Full sources and licences.
someone who can be employed as a detective to collect information