iris has 4 distinct synonyms spread across 2 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.
plants with sword-shaped leaves and erect stalks bearing bright-colored flowers composed of three petals and three drooping sepals
Synonyms, antonyms and the broader and narrower relations for iris come from Princeton University’s WordNet. Full sources and licences.
muscular diaphragm that controls the size of the pupil which in turn controls the amount of light that enters the eye; it forms the colored portion of the eye
diaphragm consisting of thin overlapping plates that can be adjusted to change the diameter of a central opening