purify has 5 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.
make pure or free from sin or guilt
“he left the monastery purified”
become clean or pure or free of guilt and sin
“The hippies came to the ashram in order to purify”
Synonyms, antonyms and the broader and narrower relations for purify come from Princeton University’s WordNet. Full sources and licences.