An oxymoron is a figure of speech that combines two contradictory terms. The word oxymoron is of Greek origin. It combines the word oxy (=sharp) and moron (=dull). Thus, oxymoron not only names a contradiction in terms, it is an oxymoron as well. Oxymoronsmay be used for achieving rhetorical effects, as in working vacation and uninvited guest. They may also result from conceptual sloppiness, as in extremely average, original copy, or same difference. Oxymorons may remain unnoticed when the meanings of the contradictory parts are not distinguished, as in spendthrift, virtual reality, and Artificial Intelligence. Typically, contradictions of this kind are resolvedby taking one term as the inferior attribute of a superior concept. For example, unbiased opinion is a kind of opinion, accurate estimate is a kind of estimate, and the reply “no comment” is not taken as a comment.