(n.) A figure in which an epithet of a contrary signification is added to a word; e. g., cruel kindness; laborious idleness.

Gordian knot absurdity ambiguity ambivalence antinomy asymmetry crux dilemma disproportion disproportionateness enigma equivocality equivocation heresy heterodoxy heterogeneity hopelessness impossibility impossible impossibleness incoherence incommensurability incompatibility inconceivability incongruity inconsistency inconsonance irony irreconcilability knot knotty point no chance node nodus nonconformability nonconformity nonplus paradox perplexity pons asinorum poser puzzle quandary self-contradiction teaser the impossible unconformability unconformity unimaginability unorthodoxy unthinkability vexed question what cannot be what cannot happen