a coherent group of tested general propositions, commonly regarded as correct, that can be used as principles of explanation and prediction for a class of phenomena: Einstein's theory of relativity.
a proposed explanation whose status is still conjectural and subject to experimentation, in contrast to well-established propositions that are regarded as reporting matters of actual fact.
Mathematics. a body of principles, theorems, or the like, belonging to one subject: number theory.
the branch of a science or art that deals with its principles or methods, as distinguished from its practice: music theory.
a particular conception or view of something to be done or of the method of doing it; a system of rules or principles: conflicting theories of how children best learn to read.
contemplation or speculation: the theory that there is life on other planets.
guess or conjecture: My theory is that he never stops to think words have consequences.
Idioms about theory
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
How to use theory in a sentence
“Our prosecutors have all too often inserted themselves into the political process based on the flimsiest of legal theories,” Barr went on.
Turn Wilson’s mathematical crank, and you get a related theory describing groups of those pieces — perhaps billiard ball molecules.How Mathematical ‘Hocus-Pocus’ Saved Particle Physics | Charlie Wood | September 17, 2020 | Quanta Magazine
She also learns immediately that this theory is “not just incorrect but hateful, like saying that different races had different IQs” — and yet, “in my heart, I knew that Whorf was right,” that language does change the way you think.The true love story in Elif Batuman’s The Idiot is a love affair with language | Constance Grady | September 11, 2020 | Vox
It applies a different random error to each piece of information that’s encoded—which in theory makes it impossible to break without knowing the key.Quantum computers threaten to end digital security. Here’s what’s being done about it | Jeremy Kahn | September 11, 2020 | Fortune
Kindrachuk also works on ebola, and he says over the years many such theories have been put forth in scientific journals without provoking this kind of response.Wearing a mask could protect you from COVID-19 in more ways than you think | Kat Eschner | September 10, 2020 | Popular-Science
But at the heart of this “Truther” conspiracy theory is the idea that “someone” wants to destroy Bill Cosby.
Is it sort of evidence of the Gladwellian 10,000 hours theory?Coffee Talk with Fred Armisen: On ‘Portlandia,’ Meeting Obama, and Taylor Swift’s Greatness | Marlow Stern | January 7, 2015 | THE DAILY BEAST
But a 2011 study of genetic evidence from 30 ethnic groups in India disproved this theory.
But, in theory, that started to change last week with the first meeting of SIX, the State Innovation Exchange.
So I was happy to see that the European theory of terroir was in action, promoting with pride the qualities of a specific region.
In the year of misery, of agony and suffering in general he had endured, he had settled upon one theory.The Homesteader | Oscar Micheaux
Dean Swift was indeed a misanthrope by theory, however he may have made exception to private life.Gulliver's Travels | Jonathan Swift
The other is the new theory: that the Bible is the work of many men whom God had inspired to speak or write the truth.God and my Neighbour | Robert Blatchford
The evolution theory alleges that they were evolved, slowly, by natural processes out of previously existing matter.God and my Neighbour | Robert Blatchford
And our surroundings at that particular moment were not the most favorable to coherent thought or plausible theory-building.Raw Gold | Bertrand W. Sinclair
British Dictionary definitions for theory
a system of rules, procedures, and assumptions used to produce a result
abstract knowledge or reasoning
a speculative or conjectural view or idea: I have a theory about that
an ideal or hypothetical situation (esp in the phrase in theory)
a set of hypotheses related by logical or mathematical arguments to explain and predict a wide variety of connected phenomena in general terms: the theory of relativity
a nontechnical name for hypothesis (def. 1)
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Scientific definitions for theory
A set of statements or principles devised to explain a group of facts or phenomena. Most theories that are accepted by scientists have been repeatedly tested by experiments and can be used to make predictions about natural phenomena. See Note at hypothesis.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Cultural definitions for theory
The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.