What does tautology mean?

Definitions for tautology
tɔˈtɒl ə dʒitau·tol·o·gy

This dictionary definitions page includes all the possible meanings, example usage and translations of the word tautology.

Princeton's WordNet

  1. tautologynoun

    (logic) a statement that is necessarily true

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

  2. tautologynoun

    useless repetition

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


  1. tautologynoun

    redundant use of words

    It is tautology to say, "Forward Planning".

  2. tautologynoun

    An expression that features tautology.

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

  3. tautologynoun

    A statement that is true for all values of its variables

  4. Etymology: From tautologia, from ταυτολογία from ταὐτός + λόγος

Samuel Johnson's Dictionary

  1. TAUTOLOGYnoun

    Repetition of the same words, or of the same sense in different words.

    Etymology: ταυτολογία; tautologie, Fr. ταῦτο and λόγος.

    All science is not tautology; the last ages have shewn us, what antiquity never saw, in a dream. Joseph Glanvill, Sceps.

    Saint Andre’s feet ne’er kept more equal time,
    Not ev’n the feet of thy own Psyche’s rhime;
    Though they in numbers as in sense excel,
    So just, so like tautology, they fell. Dryden.

    Every paper addressed to our beautiful incendiaries, hath been filled with different considerations, that enemies may not accuse me of tautology. Joseph Addison, Freeholder.


  1. tautology

    A tautology is a statement or expression that is considered universally true or valid, as it expresses the same concept or idea in different ways, often unnecessarily. In logic, it refers to a formula that is true in every possible interpretation. This term can be used in various disciplines, including linguistics, rhetoric, mathematics, and philosophy, with slightly different connotations.

Webster Dictionary

  1. Tautologynoun

    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


  1. 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

  1. 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. tautologiatauto, the same, legein, to speak.]

Matched Categories

How to pronounce tautology?

How to say tautology in sign language?


  1. Chaldean Numerology

    The numerical value of tautology in Chaldean Numerology is: 9

  2. Pythagorean Numerology

    The numerical value of tautology in Pythagorean Numerology is: 1

Popularity rank by frequency of use


Translations for tautology

From our Multilingual Translation Dictionary

Get even more translations for tautology »


Find a translation for the tautology definition in other languages:

Select another language:

  • - Select -
  • 简体中文 (Chinese - Simplified)
  • 繁體中文 (Chinese - Traditional)
  • Español (Spanish)
  • Esperanto (Esperanto)
  • 日本語 (Japanese)
  • Português (Portuguese)
  • Deutsch (German)
  • العربية (Arabic)
  • Français (French)
  • Русский (Russian)
  • ಕನ್ನಡ (Kannada)
  • 한국어 (Korean)
  • עברית (Hebrew)
  • Gaeilge (Irish)
  • Українська (Ukrainian)
  • اردو (Urdu)
  • Magyar (Hungarian)
  • मानक हिन्दी (Hindi)
  • Indonesia (Indonesian)
  • Italiano (Italian)
  • தமிழ் (Tamil)
  • Türkçe (Turkish)
  • తెలుగు (Telugu)
  • ภาษาไทย (Thai)
  • Tiếng Việt (Vietnamese)
  • Čeština (Czech)
  • Polski (Polish)
  • Bahasa Indonesia (Indonesian)
  • Românește (Romanian)
  • Nederlands (Dutch)
  • Ελληνικά (Greek)
  • Latinum (Latin)
  • Svenska (Swedish)
  • Dansk (Danish)
  • Suomi (Finnish)
  • فارسی (Persian)
  • ייִדיש (Yiddish)
  • հայերեն (Armenian)
  • Norsk (Norwegian)
  • English (English)

Word of the Day

Would you like us to send you a FREE new word definition delivered to your inbox daily?

Please enter your email address:


Use the citation below to add this definition to your bibliography:


"tautology." Definitions.net. STANDS4 LLC, 2023. Web. 3 Oct. 2023. <https://www.definitions.net/definition/tautology>.

Discuss these tautology definitions with the community:


    Are we missing a good definition for tautology? Don't keep it to yourself...

    Free, no signup required:

    Add to Chrome

    Get instant definitions for any word that hits you anywhere on the web!

    Free, no signup required:

    Add to Firefox

    Get instant definitions for any word that hits you anywhere on the web!

    Browse Definitions.net


    Are you a words master?

    lacking orderly continuity
    • A. disjointed
    • B. brilliant
    • C. squashy
    • D. hatched

    Nearby & related entries:

    Alternative searches for tautology: