# tautology

> English word · Noun · IPA /toːˈtɔl.ə.d͡ʒi/ · frequency rank #71,965

## Definitions
1. Redundant use of words, a pleonasm, an unnecessary and tedious repetition.
2. An expression that features tautology.
3. A statement that is true for all truth values of its propositional variables.
4. A statement that is true for all truth values of its Boolean atoms.

## Etymology
From Late Latin tautologia, from Ancient Greek ταὐτολογία (tautología) from ταὐτός (tautós, “the same”) + λόγος (lógos, “explanation”). By surface analysis, tauto- + -logy.

## Source
Compiled from Wiktionary via kaikki.org (CC BY-SA). Data vintage: 2026-05-06.
Canonical page: https://plainspell.com/en/word/tautology