From , from from ταὐτός ("the same") + λόγος ("explanation"), analyzed as tauto- + -logy.

• (British) IPA: /tɔˈtɒl.ə.d͡ʒi/
• (America) IPA: /tɔˈtɑl.ə.d͡ʒi/

tautology

1. (uncountable) Redundant use of words, a pleonasm, an unnecessary and tedious repetition.

   It is tautology to say, "Forward Planning".

2. (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.

3. (countable, logic, propositional logic) A statement that is true for all truth values of its propositional variables.
4. (countable, logic, first-order logic) A statement that is true for all truth values of its Boolean atoms.

• (antonym(s) of “linguistics: expression”): contradiction in terms
• (antonym(s) of “in logic”): contradiction
• (antonym(s) of “literary”): oxymoron

• French: tautologie
• German: Pleonasmus
• Portuguese: tautologia, pleonasmo, redundância
• Russian: тавтоло́гия
• Spanish: tautología, pleonasmo, redundancia

• French: tautologie, lapalissade, pléonasme, truisme
• German: Tautologie
• Italian: tautologia
• Portuguese: redundância, pleonasmo, tautologia
• Spanish: redundancia, pleonasmo, tautología (rhetoric)

• French: tautologie
• German: Tautologie
• Italian: tautologia
• Portuguese: tautologia
• Spanish: tautología