### What does **tautology** mean?

## Definitions for **tautology**tɔˈtɒl ə dʒi

#### Here are all the possible meanings and translations of the word **tautology**.

### Princeton's WordNet

tautology(noun)

(logic) a statement that is necessarily true

"the statement `he is brave or he is not brave' is a tautology"

tautology(noun)

useless repetition

"to say that something is `adequate enough' is a tautology"

### Wiktionary

tautology(Noun)

redundant use of words

It is tautology to say, "Forward Planning".

tautology(Noun)

An expression that features tautology.

The expression "raze to the ground" is a tautology, since the word "raze" includes the notion "to the ground".

tautology(Noun)

A statement that is true for all values of its variables

**Origin:** From tautologia, from ταυτολογία from ταὐτός + λόγος

### Webster Dictionary

Tautology(noun)

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

### Freebase

Tautology

In logic, a tautology is a formula which is true in every possible interpretation. Philosopher Ludwig Wittgenstein first applied the term to redundancies of propositional logic in 1921; it had been used earlier to refer to rhetorical tautologies, and continues to be used in that alternate sense. A formula is satisfiable if it is true under at least one interpretation, and thus a tautology is a formula whose negation is unsatisfiable. Unsatisfiable statements, both through negation and affirmation, are known formally as contradictions. A formula that is neither a tautology nor a contradiction is said to be logically contingent. Such a formula can be made either true or false based on the values assigned to its propositional variables. The double turnstile notation is used to indicate that S is a tautology. Tautology is sometimes symbolized by "Vpq", and contradiction by "Opq". The tee symbol is sometimes used to denote an arbitrary tautology, with the dual symbol representing an arbitrary contradiction. Tautologies are a key concept in propositional logic, where a tautology is defined as a propositional formula that is true under any possible Boolean valuation of its propositional variables. A key property of tautologies in propositional logic is that an effective method exists for testing whether a given formula is always satisfied.

### Chambers 20th Century Dictionary

Tautology

taw-tol′ō-ji,

*n.*needless repetition of the same thing in different words.—*adjs.***Tautolog′ic**,**-al**, containing tautology.—*adv.***Tautolog′ically**.—*v.i.***Tautol′ogise**, to use tautology: to repeat the same thing in different words.—*ns.***Tautol′ogism**;**Tautol′ogist**.—*adjs.***Tautol′ogous**, tautological;**Tautophon′ical**.—*n.***Tautoph′ony**, repetition of the same sound. [Gr.*tautologia*—*tauto*, the same,*legein*, to speak.]

### Numerology

Chaldean Numerology

The numerical value of tautology in Chaldean Numerology is:

**9**Pythagorean Numerology

The numerical value of tautology in Pythagorean Numerology is:

**1**

### Images & Illustrations of tautology

# Translations for **tautology**

### From our Multilingual Translation Dictionary

- tautologieCzech
- Pleonasmus, TautologieGerman
- ταυτολογίαGreek
- pleonasmo, tautología, redundanciaSpanish
- تکرارPersian
- toisto, tautologiaFinnish
- tautologie, lapalissade, pléonasme, truismeFrench
- ath-bhriathrachasScottish Gaelic
- tautológiaHungarian
- sísannaIcelandic
- tautologiaItalian
- 同語反復, トートロジー, 恒真式Japanese
- тавтологијаMacedonian
- tautologieDutch
- pleonazm, tautologiaPolish
- pleonasm, tautologieRomanian
- тавтологияRussian
- zalihost, tautologija, redundancijaSerbo-Croatian

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"tautology." *Definitions.net.* STANDS4 LLC, 2017. Web. 23 Jul 2017. <http://www.definitions.net/definition/tautology>.