crossover has 4 distinct synonyms spread across 3 of its 4 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.
the interchange of sections between pairing homologous chromosomes during the prophase of meiosis
a voter who is registered as a member of one political party but who votes in the primary of another party
Synonyms, antonyms and the broader and narrower relations for crossover come from Princeton University’s WordNet. Full sources and licences.
the appropriation of a new style (especially in popular music) by combining elements of different genres in order to appeal to a wider audience
“a jazz-classical crossover album”
a path (often marked) where something (as a street or railroad) can be crossed to get from one side to the other