theory

English Online Dictionary. What means theory‎? What does theory mean?

English

Etymology

From Middle French théorie, from Late Latin theōria, from Ancient Greek θεωρία (theōría, “contemplation, speculation, a looking at, things looked at”), from θεωρέω (theōréō, “I look at, view, consider, examine”), from θεωρός (theōrós, “spectator”), from θέα (théa, “view”) + ὁράω (horáō, “I see, look”) [i. e. θέαν ὁράω (théan horáō, “see, look at a view; survey + genitive”)].

Pronunciation

• (Received Pronunciation, General Australian) IPA^(key): /ˈθɪə.ɹi/, /ˈθiː.ə.ɹi/, /ˈθɪɹ.i/
• (General American) IPA^(key): /ˈθɪɚ.i/, /ˈθi.ə.ɹi/

• Rhymes: -ɪəɹi, -iːəɹi

Noun

theory (countable and uncountable, plural theories)

2. A description of an event or system that is considered to be accurate.
4. (sciences) A coherent statement or set of ideas that explains observed facts or phenomena and correctly predicts new facts or phenomena not previously observed, or which sets out the laws and principles of something known or observed; a hypothesis confirmed by observation, experiment etc. [from 17th c.]
   • 1843, John Stuart Mill, ""A System of Logic, Ratiocinative and Inductive, ..., Bk V, Ch 7:

     In its most proper acceptation, theory means the completed result of philosophical induction from experience.
6. (uncountable) The underlying principles or methods of a given technical skill, art etc., as opposed to its practice. [from 17th c.]
8. (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.

10. A hypothesis or conjecture. [from 18th c.]
12. (countable, logic) A set of axioms together with all statements derivable from them; or, a set of statements which are deductively closed. Equivalently, a formal language plus a set of axioms (from which can then be derived theorems). The statements may be required to all be bound (i.e., to have no free variables).

    A theory is consistent if it has a model.

14. (obsolete) Mental conception; reflection, consideration. [16th–18th c.]

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”.

Synonyms

• See also Thesaurus:supposition

Meronyms

• (in logic): axioms

Holonyms

• (in logic): formal system

Derived terms

Related terms

Translations

See also

• axiom
• postulate
• proposition

References

• “theory”, in OneLook Dictionary Search.
• theory in Keywords for Today: A 21st Century Vocabulary, edited by The Keywords Project, Colin MacCabe, Holly Yanacek, 2018.
• "theory" in Raymond Williams, Keywords (revised), 1983, Fontana Press, page 316.
• “theory”, in The Century Dictionary […], New York, N.Y.: The Century Co., 1911, →OCLC.

Anagrams

• Yother, thyreo-