refutation has 6 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.
the speech act of answering an attack on your assertions
“his refutation of the charges was short and persuasive”
any evidence that helps to establish the falsity of something
the act of determining that something is false
Synonyms, antonyms and the broader and narrower relations for refutation come from Princeton University’s WordNet. Full sources and licences.