prime has 17 distinct synonyms spread across 7 of its 12 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. WordNet records no antonym for it — antonymy is a relation between word forms rather than concepts, so it is deliberately sparse.
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.
a natural number that has exactly two distinct natural number divisors: 1 and itself
insert a primer into (a gun, mine, or charge) preparatory to detonation or firing
“prime a cannon”
2 of the 12 recorded senses carry no synonym, antonym or related term, so they are not shown above. Every sense, with its definition and examples, is on the full entry for prime.
Synonyms, antonyms and the broader and narrower relations for prime come from Princeton University’s WordNet. Full sources and licences.
the second canonical hour; about 6 a.m.
fill with priming liquid
“prime a car engine”