contradictory has 5 distinct synonyms spread across 3 of its 5 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.
that confounds or contradicts or confuses
in disagreement
“the figures are at odds with our findings”
unable for both to exist or be true at the same time
two propositions are contradictories if both cannot be true (or both cannot be false) at the same time
1 of the 5 recorded senses carries no synonym, antonym or related term, so it is not shown above. Every sense, with its definition and examples, is on the full entry for contradictory.
Synonyms, antonyms and the broader and narrower relations for contradictory come from Princeton University’s WordNet. Full sources and licences.