gillyflower has 4 distinct synonyms spread across 2 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 several Old World plants cultivated for their brightly colored flowers
Eurasian plant with pink to purple-red spice-scented usually double flowers; widely cultivated in many varieties and many colors
Synonyms, antonyms and the broader and narrower relations for gillyflower come from Princeton University’s WordNet. Full sources and licences.