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**noun:**

- Redundant use of words, a pleonasm, an unnecessary and tedious repetition.
- [[File:Wikipedia-logo.png|44px|none|link=|alt=]] English Wikipedia has an article on: Tautology (logic)Wikipedia (countable, logic) In propositional logic: a statement that is true for all truth values of its propositional variables. In first-order logic: a statement that is true for all truth values of its Boolean atoms.
- An expression that features tautology.