Noun

(obsolete) Mental conception; reflection, consideration.

* 1646 , (Thomas Browne), Pseudodoxia Epidemica , VII.19:

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

(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.

* 2002 , Duncan Steel, The Guardian , 23 May 2002:

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.

* 2003 , (Bill Bryson), A Short History of Nearly Everything , BCA, p. 118:

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

* 2009 , (Richard Dawkins), The Greatest Show On Earth: The Evidence for Evolution , Bantam, p. 10:

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 ".

* {{quote-magazine, date=2012-01

, author=Michael Riordan , title=Tackling Infinity , volume=100, issue=1, page=86 , magazine= citation , passage=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 .}}

(uncountable) The underlying principles or methods of a given technical skill, art etc., as opposed to its practice.

* 1990 , Tony Bennett, Outside Literature , p. 139:

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

* 1998 , Elizabeth Souritz, The Great History of Russian Ballet :

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

(mathematics) A field of study attempting to exhaustively describe a particular class of constructs.

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

A hypothesis or conjecture.

* 1999 , Wes DeMott, Vapors :

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?

* 2003 , Sean Coughlan, The Guardian , 21 Jun 2003:

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

(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.

Noun

The result or outcome of a cause. See below.

*

, title=(The Celebrity), chapter=1 , passage=The stories did not seem to me to touch life. They were plainly intended to have a bracing moral effect , and perhaps had this result for the people at whom they were aimed.}}

* {{quote-book, year=1963, author=(Margery Allingham), title=(The China Governess)

, chapter=1 citation , passage=The half-dozen pieces […] were painted white and carved with festoons of flowers, birds and cupids. […]  The bed was the most extravagant piece.  Its graceful cane halftester rose high towards the cornice and was so festooned in carved white wood that the effect was positively insecure, as if the great couch were trimmed with icing sugar.}}

* {{quote-magazine, date=2013-06-08, volume=407, issue=8839, page=55, magazine=(The Economist)

, title= Obama goes troll-hunting , passage=The solitary, lumbering trolls of Scandinavian mythology would sometimes be turned to stone by exposure to sunlight. Barack Obama is hoping that several measures announced on June 4th will have a similarly paralysing effect on their modern incarnation, the patent troll.}}

Impression left on the mind; sensation produced.

* J. C. Shairp

patchwork introduced for oratorical effect

* Washington Irving

The effect was heightened by the wild and lonely nature of the place.

(filmology) An illusion produced by technical means (as in "special effect")

(sound engineering) An alteration in sound after it has been produced by an instrument.

(sound engineering) A device for producing an alteration in sound produced by an instrument.

Execution; performance; realization; operation.

* Shakespeare

That no compunctious visitings of nature / Shake my fell purpose, nor keep peace between / The effect and it.

# (uncountable) The state of being binding and enforceable, as in a rule, policy, or law.

A scientific phenomenon, usually named after its discoverer.

(usually plural) Belongings, usually as personal effects.

Consequence intended; purpose; meaning; general intent; with to .

* Bible, Chron. xxxiv. 22

They spake to her to that effect .

(obsolete) Reality; actual meaning; fact, as distinguished from mere appearance.

* Denham

no other in effect than what it seems

(obsolete) Manifestation; expression; sign.

* Shakespeare

All the large effects / That troop with majesty.