tautology Meaning, Definition & Usage

noun (logic) a statement that is necessarily true
- the statement `he is brave or he is not brave' is a tautology
noun useless repetition
- to say that something is `adequate enough' is a tautology

L. tautologia, Gr. : cf. F. tautologie.

(Rhet.) A repetition of the same meaning in different words; needless repetition of an idea in different words or phrases; a representation of anything as the cause, condition, or consequence of itself, as in the following lines: --
The dawn is overcast, the morning lowers, And heavily in clouds brings on the day. Addison.
Syn. -- Repetition. -- Tautology, Repetition. There may be frequent repetitions (as in legal instruments) which are warranted either by necessity or convenience; but tautology is always a fault, being a sameness of expression which adds nothing to the sense or the sound.