noun

• An apparently self-contradictory statement, which can only be true if it is false, and vice versa.
• A counterintuitive conclusion or outcome.
• A claim that two apparently contradictory ideas are true.
• A thing involving contradictory yet interrelated elements that exist simultaneously and persist over time.
• A person or thing having contradictory properties.
• An unanswerable question or difficult puzzle, particularly one which leads to a deeper truth.
• (obsolete) A statement which is difficult to believe, or which goes against general belief.
• (uncountable) The use of counterintuitive or contradictory statements (paradoxes) in speech or writing.
• (uncountable, philosophy) A state in which one is logically compelled to contradict oneself.
• (countable, uncountable, psychotherapy) The practice of giving instructions that are opposed to the therapist's actual intent, with the intention that the client will disobey or be unable to obey.