winter melon has 4 distinct synonyms 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 a variety of muskmelon vines having fruit with a smooth white rind and white or greenish flesh that does not have a musky smell
the fruit of the winter melon vine; a green melon with pale green to orange flesh that keeps well
Synonyms, antonyms and the broader and narrower relations for winter melon come from Princeton University’s WordNet. Full sources and licences.