- (uncountable) Redundant use of words, a pleonasm, an unnecessary and tedious repetition.
- It is tautology to say, "Forward Planning".
- (countable) An expression that features tautology.
- The expression "raze to the ground" is a tautology, since the word "raze" includes the notion "to the ground".
- 1946, Bertrand Russell, History of Western Philosophy:
- Pure mathematics consists of tautologies, analogous to ‘men are men’, but usually more complicated.
- (countable, logic, propositional logic) A statement that is true for all truth values of its propositional variables.
- (countable, logic, first-order logic) A statement that is true for all truth values of its Boolean atoms.
terms derived from tautology (noun)
uncountable: redundant use of words
expression that features tautology