winter squash has 1 distinct synonym spread across 1 of its 2 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 various plants of the species Cucurbita maxima and Cucurbita moschata producing squashes that have hard rinds and mature in the fall
any of various fruits of the gourd family with thick rinds and edible yellow to orange flesh that mature in the fall and can be stored for several months
Synonyms, antonyms and the broader and narrower relations for winter squash come from Princeton University’s WordNet. Full sources and licences.