An oxymoron (plural oxymorons or more rarely oxymora) is a figure of speech that combines two normally contradictory terms. Oxymoron is a loanword from Greek oxy ("sharp") and moros ("dull"). Thus the word oxymoron is itself an oxymoron.
Oxymora are a proper subset of the expressions called contradictions in terms. What distinguishes oxymora from other paradoxes and contradictions is that they are used intentionally, for rhetorical effect, and the contradiction is only apparent, as the combination of terms provides a novel expression of some concept, such as "cruel to be kind".
The most common form of oxymoron involves an adjective-noun combination. For example, the following line from Tennyson's Idylls of the King contains two oxymora:
Oxymora can also be wooden irons in that they are in violation of the Principle of contradiction which asserts that nothing can be thought if it contains contradictory characteristics, predicates, attributes, or qualities.citation needed]