Tautology definitions
An empty or vacuous statement composed of simpler statements in a fashion that makes it logically true whether the simpler statements are factually true or false; for example, the statement Either it will rain tomorrow or it will not rain tomorrow.
noun
The definition of a tautology is a statement that says the same thing twice in different ways, or a statement that has to be true by the way it is phrased.
The statement "the reason is because" is an example of a tautology because "the reason" and "because" are essentially the same thing said twice in different ways.
The statement "it is either right or it is left" is an example of a tautology because the statement by definition always has to be true.
noun
Needless repetition of the same sense in different words; redundancy.
noun
An instance of such repetition.
noun
Needless repetition of an idea in different words; redundancy; pleonasm (Ex.: “necessary essentials”)
noun
An instance of such repetition.
noun
(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".
noun
Given a Boolean A, "A OR (NOT A)" is a tautology.
A logical statement which is neither a tautology nor a contradiction is a contingency.
A tautology can be verified by constructing a truth tree for its negation: if all of the leaf nodes of such truth tree end in X's, then the original (pre-negated) formula is a tautology.
noun
Origin of tautology
From Late Latin tautologia, from Ancient Greek ταυτολογία (tautologÃa) from ταá½Ï„ός (tautós, “the same") + λόγος (lógos, “explanation")