First attested in the 17th century, noun use of 5th century Latinoxymōrum(adj), neut. nom. form of oxymōrus(adj), from Ancient Greekὀξύμωρος(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.
(rhetoric) A figure of speech in which two words or phrases with opposing meanings are used together intentionally for effect.
[1835, L[arret] Langley, A Manual of the Figures of Rhetoric,[…], Doncaster: Printed by C. White, Baxter-Gate, OCLC1062248511, page 35:
In Oxymoron jarring phrases join And terms opposed in harmony combine.]
1996, John Sinclair, "Culture and Trade: Some Theoretical and Practical Considerations", in Emile G. McAnany, Kenton T. Wilkinson (eds.), Mass Media and Free Trade: NAFTA and the Cultural Industries, University of Texas Press
For Theodor Adorno and his colleagues at the Frankfurt School who coined the term, "culture industry" was an oxymoron, intended to set up a critical contrast between the exploitative, repetitive mode of industrial mass production under capitalism and the associations of transformative power and aesthetico-moral transcendence that the concept of culture carried in the 1940s, when it still meant "high" culture.
Historically, an oxymoron was "a paradox with a point", or "pointedly foolish: a witty saying, the more pointed from being paradoxical or seemingly absurd" at first glance. Its deliberate purpose was to underscore a point or to draw attention to a concealed point. The common vernacular use of oxymoron as simply a contradiction in terms is considered incorrect by some speakers and writers, and is perhaps best avoided in certain contexts.