transubstantiation has 1 distinct synonym spread across 1 of its 2 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 Roman Catholic doctrine that the whole substance of the bread and the wine changes into the substance of the body and blood of Christ when consecrated in the Eucharist
an act that changes the form or character or substance of something
Synonyms, antonyms and the broader and narrower relations for transubstantiation come from Princeton University’s WordNet. Full sources and licences.