A phrase or expression that causes confusion because it contains words or ideas that contradict each other; an oxymoron. Jumbo shrimp is such a contradiction in terms.
a statement containing a seeming contradiction. A wealthy pauper is a contradiction in terms.A straight-talking politician may seem to be a contradiction in terms.
A statement that seems to contradict itself, with one part of it denying another. For example, I've always believed that "a poor millionaire" was a contradiction in terms. [Late 1700s]