sweet sultan has 5 distinct synonyms spread across 3 of its 3 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.
annual of Mediterranean to Portugal having hairy stems and minutely spiny-toothed leaves and large heads of yellow flowers
perennial of mountains of Iran and Iraq; cultivated for its fragrant rose-pink flowers
Asian plant widely grown for its sweetly fragrant pink flowers; sometimes placed in genus Centaurea
Synonyms, antonyms and the broader and narrower relations for sweet sultan come from Princeton University’s WordNet. Full sources and licences.