Definition of: oxymoron

(ok′si·môr′on, -mō′ron) noun plural ·mo·ra (-môr′ə, -mō′rə)
A figure of speech consisting of that form of antithesis in which, for emphasis or in an epigram, contradictory terms are brought sharply together, as in the phrase; “O heavy lightness, serious vanity!” [<Gk. oxymōron, neut. of oxymōros <oxys keen + mōros foolish]