prophecy has 3 distinct synonyms spread across 2 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.
knowledge of the future (usually said to be obtained from a divine source)
a prediction uttered under divine inspiration
Synonyms, antonyms and the broader and narrower relations for prophecy come from Princeton University’s WordNet. Full sources and licences.