Dictionary > English Dictionary > Definition, synonym and antonym of theory
Meaning of theory by Wiktionary Dictionary



    From Late Latin theōria, from Ancient Greek θεωρία ( theōria, “contemplation, speculation, a looking at, things looked at” ), from θεωρέω ( theōreō, “I look at, view, consider, examine” ), from θεωρός ( theōros, “spectator” ), from θέα ( thea, “a view” ) + ὁράω ( horaō, “I see,look” ) .


    • ( UK ) IPA: /ˈθɪəɹi/
    • Rhymes: -ɪəri


    theory ( countable and uncountable; plural: theories )

    1. ( obsolete ) Mental conception; reflection, consideration. [16th-18th c.]
    2. ( sciences ) A coherent statement or set of ideas that explains observed facts or phenomena, or which sets out the laws and principles of something known or observed; a hypothesis confirmed by observation, experiment etc. [from 17th c.]
    3. ( uncountable ) The underlying principles or methods of a given technical skill, art etc., as opposed to its practice. [from 17th c.]
    4. ( mathematics ) A field of study attempting to exhaustively describe a particular class of constructs. [from 18th c.]
      Knot theory classifies the mappings of a circle into 3-space .
    5. A hypothesis or conjecture. [from 18th c.]
    6. ( countable ) ( logic ) A set of axioms together with all statements derivable from them. Equivalently, a formal language plus a set of axioms ( from which can then be derived theorems ) .
      A theory is consistent if it has a model .

    Usage notes

    In scientific discourse, the sense “unproven conjecture” is discouraged ( with hypothesis or conjecture preferred ), due to unintentional ambiguity and intentional equivocation with the sense “well-developed statement or structure” .


    • See also Wikisaurus:supposition



    Related terms

Explanation of theory by Wordnet Dictionary


    1. a tentative insight into the natural world

    2. a scientific hypothesis that survives experimental testing becomes a scientific theory
      he proposed a fresh theory of alkalis that later was accepted in chemical practices
    3. a belief that can guide behavior

    4. the architect has a theory that more is less
      they killed him on the theory that dead men tell no tales
    5. a well-substantiated explanation of some aspect of the natural world

    6. theories can incorporate facts and laws and tested hypotheses
      true in fact and theory

    Definition of theory by GCIDE Dictionary


    1. Theory n.; pl. Theories [F. théorie, L. theoria, Gr. a beholding, spectacle, contemplation, speculation, fr. a spectator, to see, view. See Theater.]
      1. A doctrine, or scheme of things, which terminates in speculation or contemplation, without a view to practice; hypothesis; speculation.

      ☞ “This word is employed by English writers in a very loose and improper sense. It is with them usually convertible into hypothesis, and hypothesis is commonly used as another term for conjecture. The terms theory and theoretical are properly used in opposition to the terms practice and practical. In this sense, they were exclusively employed by the ancients; and in this sense, they are almost exclusively employed by the Continental philosophers.” Sir W. Hamilton.

      2. An exposition of the general or abstract principles of any science; as, “the theory of music”.

      3. The science, as distinguished from the art; as, “the theory and practice of medicine”.

      4. The philosophical explanation of phenomena, either physical or moral; as, “Lavoisier's theory of combustion; Adam Smith's theory of moral sentiments.”

      Atomic theory, Binary theory, etc. See under Atomic, Binary, etc.

      Syn. -- Hypothesis, speculation. -- Theory, Hypothesis. A theory is a scheme of the relations subsisting between the parts of a systematic whole; an hypothesis is a tentative conjecture respecting a cause of phenomena.