theory

plural theories

1. countableuncountableA description of an event or system that is considered to be accurate.

   As they encrease the hatred of vice in some, so doe they enlarge the theory of wickednesse in all.

   1646, Thomas Browne, Pseudodoxia Epidemica, VII.19

2. countableuncountablesciencesA 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.First known use 17th c.

   Does this mean, then, that there can be no such thing as a theory of literature?

   1990, Tony Bennett, Outside Literature, page 139

   5 more examples

   In its most proper acceptation, theory means the completed result of philosophical induction from experience.

   1843, John Stuart Mill, ""A System of Logic, Ratiocinative and Inductive, ..., Bk V, Ch 7

   It was only when Einstein's theory of relativity was published in 1915 that physicists could show that Mercury's "anomaly" was actually because Newton's gravitational theory was incomplete.

   2002 May 23, Duncan Steel, The Guardian

   The world would need additional decades [...] before the Big Bang would begin to move from interesting idea to established theory.

   2003, Bill Bryson, A Short History of Nearly Everything, BCA, page 118

   Scientists and creationists are understanding the word "theory" in two very different senses. Evolution is a theory in the same sense as the heliocentric theory. In neither case should the word "only" be used, as in "only a theory".

   2009, Richard Dawkins, The Greatest Show On Earth: The Evidence for Evolution, Bantam, page 10

   Some of the most beautiful and thus appealing physical theories, including quantum electrodynamics and quantum gravity, have been dogged for decades by infinities that erupt when theorists try to prod their calculations into new domains. Getting rid of these nagging infinities has probably occupied far more effort than was spent in originating the theories.

   2012 January 28, Michael Riordan, “Tackling Infinity”, in American Scientist, volume 100, number 1, archived from the original on 30 Apr 2013, page 86

3. uncountableThe underlying principles or methods of a given technical skill, art etc., as opposed to its practice.First known use 17th c.

   Lopukhov wrote a number of books and articles on ballet theory, as well as his memoirs.

   1998, Elizabeth Souritz, The Great History of Russian Ballet

   Antonyms: praxis

4. countableuncountablemathematicsA field of study attempting to exhaustively describe a particular class of constructs.First known use 18th c.

   Knot theory classifies the mappings of a circle into 3-space.

   2 more examples

   It's just a theory I have, and I wonder if women would agree. But don't men say a lot about themselves when a short-skirted woman slides out of a car or chair?

   1999, Wes DeMott, Vapors

   The theory is that by stripping costs to the bone, they are able to offer ludicrously low fares.

   2003 June 21, Sean Coughlan, The Guardian

5. countablehuman sciencesA 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.

6. countableuncountablechess and similar gamesThe standardization and study of fixed sequences of moves, especially in the opening phase of a game.

   Near-synonym: joseki

   Synonyms: joseki

7. countableobsoleteuncountableMental conception; reflection, consideration.First known use 16th–18th c.
8. countableinformaluncountableA hypothesis or conjecture.First known use 18th c.