transmutation has 3 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.
an act that changes the form or character or substance of something
a qualitative change
(physics) the change of one chemical element into another (as by nuclear decay or radioactive bombardment)
“the transmutation of base metals into gold proved to be impossible”
Synonyms, antonyms and the broader and narrower relations for transmutation come from Princeton University’s WordNet. Full sources and licences.