separate has 34 distinct synonyms spread across 15 of its 19 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 joint.
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.
discontinue an association or relation; go different ways
“The business partners broke over a tax question”
treat differently on the basis of sex or race
independent; not united or joint
“a problem consisting of two separate issues”
standing apart; not attached to or supported by anything
“a freestanding bell tower”
have the connection undone; having become separate
a garment that can be purchased separately and worn in combinations with other garments
1 of the 19 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 separate.
Synonyms, antonyms and the broader and narrower relations for separate come from Princeton University’s WordNet. Full sources and licences.