cordarone has 1 distinct synonym 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.
an antiarrhythmic drug (trade name Cordarone) that has potentially fatal side effects and is used to control serious heart rhythm problems only when safer agents have been ineffective
Synonyms, antonyms and the broader and narrower relations for cordarone come from Princeton University’s WordNet. Full sources and licences.