triiodothyronine has 2 distinct synonyms spread across 1 of its 1 sense. 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.
thyroid hormone similar to thyroxine but with one less iodine atom per molecule and produced in smaller quantity; exerts the same biological effects as thyroxine but is more potent and briefer
Synonyms, antonyms and the broader and narrower relations for triiodothyronine come from Princeton University’s WordNet. Full sources and licences.