Definitions

1. noun

A statement or expression that repeats something already said or implied, often to the point of being unnecessary or obvious.

“The phrase ‘free gift’ is an example of tautology, as ‘gift’ implies that it is free.”

2. noun

A term or phrase in logic that is always true, regardless of the values assigned to its variables, often used to illustrate a logical fallacy.

“The statement ‘all bachelors are unmarried’ is a tautology in logic, as it is always true.”