paradox

Concise Oxford English Dictionary © 2008 Oxford University Press:
paradox/ˈparədɒks/

▶noun

• 1 a seemingly absurd or self-contradictory statement or proposition that may in fact be true.

  ■ an apparently sound statement or proposition which leads to a logically unacceptable conclusion.

• 2 a person or thing that combines contradictory features or qualities.

– derivatives
paradoxical adjective,
paradoxically adverb.

– origin C16 (orig. denoting a statement contrary to accepted opinion): via late L. from Gk paradoxon ‘contrary (opinion)’.