oxymoron

First attested in the 17th century, noun use of 5th century Latin oxymōrum (adjective), neut. nom. form of oxymōrus (adjective), from Ancient Greek ὀξύμωρος (oxúmōros), compound of ὀξύς (oxús, “sharp, keen, pointed”) (English oxy-, as in oxygen) + μωρός (mōrós, “dull, stupid, foolish”) (English moron (“stupid person”)). Literally "sharp-dull", "keen-stupid", or "pointed-foolish" – itself an oxymoron, hence autological; compare sophomore (literally “wise fool”), influenced by similar analysis. The compound form ὀξύμωρον (oxúmōron) is not found in the extant Ancient Greek sources.