toy has 8 distinct synonyms spread across 6 of its 8 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.
a nonfunctional replica of something else (frequently used as a modifier)
“a toy stove”
a device regarded as providing amusement
“private airplanes are a rich man's toy”
Synonyms, antonyms and the broader and narrower relations for toy come from Princeton University’s WordNet. Full sources and licences.