Paradox (noun)

1. A statement or situation that contradicts itself or seems to go against common sense.
2. An assertion that is apparently self-contradictory or absurd but in reality expresses a possible truth.

Origin:

From the greek word "paradoxos" meaning "contrary to expectations, existing belief or perceived opinion".

Examples:

1. The statement "this sentence is false" is a paradox.
2. It is a paradox that the more you try to avoid failure, the more likely you are to experience it.
3. The paradox of choice is that having too many options can make it harder to make a decision.
4. The scientist's explanation of the phenomenon was full of paradoxes and contradictions.
5. The old man's words were paradoxical, but they made perfect sense.