squash has 7 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.
any of numerous annual trailing plants of the genus Cucurbita grown for their fleshy edible fruits
edible fruit of a squash plant; eaten as a vegetable
a game played in an enclosed court by two or four players who strike the ball with long-handled rackets
Synonyms, antonyms and the broader and narrower relations for squash come from Princeton University’s WordNet. Full sources and licences.