a statement or proposition that seems self-contradictory or absurd but in reality expresses a possible truth.

a self-contradictory and false proposition.

any person, thing, or situation exhibiting an apparently contradictory nature.

an opinion or statement contrary to commonly accepted opinion.

noun

absurdity , ambiguity , anomaly , catch , catch-22 * , enigma , error , inconsistency , mistake , mystery , nonsense , oddity , opposite , reverse , antinomy , contradiction , puzzle