A theory is a formal idea or set of ideas that is intended to explain something.
Marx produced a new theory about historical change based upon conflict.
Einstein formulated the Theory of Relativity in 1905. [+ of]
Synonyms: hypothesis, philosophy, system of ideas, plan More Synonyms of theory
2. countable noun
If you have a theory about something, you have your own opinion about it which you cannot prove but which you think is true.
There was a theory that he wanted to marry her.
My theory is that you don't need a gym if you have stairs.
Synonyms: belief, feeling, speculation, assumption More Synonyms of theory
3. uncountable noun
The theory of a practical subject or skill is the set of rules and principles that form the basis of it.
He taught us music theory.
...graduates who are well-trained in both the theory and practice of statistics.
[Also + of]
4.
See in theory
theory in British English
(ˈθɪərɪ)
nounWord forms: plural-ries
1.
a system of rules, procedures, and assumptions used to produce a result
2.
abstract knowledge or reasoning
3.
a speculative or conjectural view or idea
I have a theory about that
4.
an ideal or hypothetical situation (esp in the phrase in theory)
5.
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
6. a nontechnical name for hypothesis (sense 1)
Word origin
C16: from Late Latin theōria, from Greek: a sight, from theōrein to gaze upon
theory in American English
(ˈθiəri; ˈθɪri)
nounWord forms: pluralˈtheories
1. Obsolete
a mental viewing; contemplation
2.
a speculative idea or plan as to how something might be done
3.
a systematic statement of principles involved
the theory of equations in mathematics
4.
a formulation of apparent relationships or underlying principles of certain observed phenomena which has been verified to some degree
5.
that branch of an art or science consisting in a knowledge of its principles and methods rather than in its practice; pure, as opposed to applied, science, etc.
6. Popularly
a mere conjecture, or guess
SYNONYMY NOTE: theory, as compared here, implies considerable evidence in support of a formulated generalprinciple explaining the operation of certain phenomena [the theory of evolution]; hypothesis implies an inadequacy of evidence in support of an explanation that is tentativelyinferred, often as a basis for further experimentation [the nebular hypothesis]; law implies an exact formulation of the principle operating in a sequence of events innature, observed to occur with unvarying uniformity under the same conditions [the law of the conservation of energy]
Word origin
< Fr or LL: Fr théorie < LL theoria < Gr theōria, a looking at, contemplation, speculation, theory < theōrein: see theorem
COBUILD Collocations
theory
disprove a theory
economic theory
Marxist theory
modernization theory
scientific theory
test a theory
theory is correct
Examples of 'theory' in a sentence
theory
There are three main theories about why this is.
Times, Sunday Times (2016)
We have two theories to explain the world.
Times, Sunday Times (2016)
It is the product of an absurd conspiracy theory.
Times, Sunday Times (2017)
Economic theory is clear on the issue.
Times, Sunday Times (2016)
It can in theory go after any assets.
Times, Sunday Times (2016)
It has been a magnet for conspiracy theories.
Times, Sunday Times (2016)
Theory and practice are very different, though.
Times, Sunday Times (2017)
Thousands of years on, theory still rings true.
The Sun (2016)
A further 111 people were convicted of taking practical or theory tests on behalf of others.
Times, Sunday Times (2017)
And I have a theory about it.
The Sun (2016)
They also write an extended essay and study theories of knowledge.
Times, Sunday Times (2010)
But we seem to prove all these theories wrong.
The Sun (2013)
What seems so intuitively true in theory is not always so in practice.
Al Ries and Laura Ries THE 22 IMMUTABLE LAWS OF BRANDING (2002)
Fitness instructors rarely explain the theory behind their routines.
Times, Sunday Times (2016)
This intuitive approach will help you understand how the theory works in practice.
Mishkin, Frederic S. Financial Markets, Institutions and Money (1995)
The question then is whether political theory can provide the planner with something better than opinion.
Low, Nicholas Politics, Planning and the State (1990)
This means it is difficult to test theories and ideas.
Times, Sunday Times (2013)
How does the hypothesis fit in with other hypotheses or more general theory?
Porush, David A Short Guide to Writing About Science (1995)
The task now becomes one of realizing theory through practical struggle.
Boyne, Roy Foucault and Derrida - The Other Side Of Reason (1990)
This is to supplement economic theory with an understanding of politics and human nature.
Times, Sunday Times (2008)
What are the major differences between theories of societal change?
Appelbaum, Richard P. Sociology (1995)
Theories come and go as our factual knowledge increases.
Yearley, Steven Science, Technology, and Social Change (1988)
Talking up conspiracy theories is one thing.
The Sun (2016)
There are conflicting theories about the purpose of sleep.
Times, Sunday Times (2007)
The displacement of subject theory out of philosophy occurred a long time ago.
The Times Literary Supplement (2013)
There are two theories about the delay.
Times, Sunday Times (2007)
This theory is also true for larger roasts.
The Sun (2016)
But then he was challenged to put his theories into practice.
Christianity Today (2000)
This combined ideas of number theory with the geometry of surfaces.
Times, Sunday Times (2007)
Equally important is the decline in public interest in political theory and in the details of party policies.
Times, Sunday Times (2010)
We knew we were seeing something beyond what we have seen before and beyond what current theories can explain.
Times, Sunday Times (2010)
It could only be understood and interpreted within the framework of a " general economic theory of capitalism".
Ramirez-Faria, Carlos The Origins of Economic Inequality between Nations: A critique of Western theorieson development and underdevelopment (1990)
Knowledge and theory move forward together in a kind of uneasy, shuffling collaboration.
Richard Fortey THE EARTH: An Intimate History (2004)
The problem is that none of the alternative theories can be proved with convincing evidence, either.
Times, Sunday Times (2008)
In other languages
theory
British English: theory /ˈθɪərɪ/ NOUN
A theory is a formal idea or set of ideas intended to explain something.
...the theory of evolution.
American English: theory
Arabic: نَظَرِيَّة
Brazilian Portuguese: teoria
Chinese: 理论
Croatian: teorija
Czech: teorie
Danish: teori
Dutch: theorie
European Spanish: teoría
Finnish: teoria
French: théorie
German: Theorie
Greek: θεωρία
Italian: teoria
Japanese: 理論
Korean: 이론
Norwegian: teori
Polish: teoria
European Portuguese: teoria
Romanian: teorie
Russian: теория
Latin American Spanish: teoría
Swedish: teori
Thai: ทฤษฎี
Turkish: kuram
Ukrainian: теорія
Vietnamese: lý thuyết
All related terms of 'theory'
in theory
You use in theory to say that although something is supposed to be true or to happen in the way stated, it may not in fact be true or happen in that way.
band theory
a theory of the electrical properties of metals, semiconductors , and insulators based on energy bands
Bohr theory
a theory of atomic structure that explains the spectrum of hydrogen atoms. It assumes that the electron orbiting around the nucleus can exist only in certain energy states, a jump from one state to another being accompanied by the emission or absorption of a quantum of radiation
game theory
mathematical theory concerned with the optimum choice of strategy in situations involving a conflict of interest
germ theory
the theory that all infectious diseases are caused by microorganisms
set theory
the branch of mathematics concerned with the properties and interrelationships of sets
wave theory
the theory proposed by Huygens that light is transmitted by waves
atomic theory
any theory in which matter is regarded as consisting of atoms , esp that proposed by John Dalton postulating that elements are composed of atoms that can combine in definite proportions to form compounds
auteur theory
the theory that creative directors are the major force in film-making
chaos theory
a theory, applied in various branches of science , that apparently random phenomena have underlying order
domino theory
a foreign policy theory speculating that a political event in one nation will cause similar events in neighbouring nations
field theory
a theory in which the basic quantities are physical fields
formal theory
an uninterpreted symbolic system whose syntax is precisely defined , and on which a relation of deducibility is defined in purely syntactic terms; a logistic system
Galois theory
the theory applying group theory to solving algebraic equations
games theory
mathematical theory concerned with the optimum choice of strategy in situations involving a conflict of interest
gauge theory
a type of theory of elementary particles designed to explain the strong, weak , and electromagnetic interactions in terms of exchange of virtual particles
graph theory
the branch of mathematics dealing with linear graphs
group theory
the branch of algebra that deals with mathematical groups
model theory
the branch of logic that deals with the properties of models ; the semantic study of formal systems
number theory
the study of integers , their properties, and the relationship between integers
proof theory
the branch of logic that studies the syntactic properties of formal theories, esp the syntactic characterization of deductive validity
string theory
a branch of theoretical physics
theory-laden
(of an expression ) capable of being understood only within the context of a specific theory, as for example superego , which requires the apparatus of Freudian theory in explanation
automata theory
the formal study of the power of computation of abstract machines
decision theory
the study of strategies for decision-making under conditions of uncertainty in such a way as to maximize the expected utility
economic theory
The theory of a practical subject or skill is the set of rules and principles that form the basis of it.
identity theory
a form of materialism which holds mental states to be identical with certain states of the brain and so to have no separate existence , but regards this identity as contingent so that mentalistic and physicalistic language are not held to be synonymous
kinetic theory
the theory that the minute particles of all matter are in constant motion and that the temperature of a substance is dependent on the velocity of this motion, increased motion being accompanied by increased temperature: according to the kinetic theory of gases, the elasticity , diffusion , pressure, and other physical properties of a gas are due to the rapid motion in straight lines of its molecules , to their impacts against each other and the walls of the container , to weak cohesive forces between molecules, etc.
literary theory
the systematic analysis and study of literature using general principles
Marxist theory
A theory is a formal idea or set of ideas that is intended to explain something.
quantity theory
a theory stating that the general price level varies directly with the quantity of money in circulation and the velocity with which it is circulated , and inversely with the volume of production expressed by the total number of money transactions
quantum theory
a theory concerning the behaviour of physical systems based on Planck's idea that they can only possess certain properties, such as energy and angular momentum , in discrete amounts ( quanta ). The theory later developed in several equivalent mathematical forms based on De Broglie's theory and on the Heisenberg uncertainty principle
queuing theory
a mathematical approach to the rate at which components queue to be processed by a machine, instructions are accessed by a computer, orders need to be serviced, etc, to achieve the optimum flow
systems theory
an approach to industrial relations which likens the enterprise to an organism with interdependent parts, each with its own specific function and interrelated responsibilities
attribution theory
the theory that tries to explain how people link actions and emotions to particular causes, both internal and external
catastrophe theory
a mathematical theory that classifies surfaces according to their form
complexity theory
the study of complex systems, including subjects such as chaos theory and genetic algorithms
conspiracy theory
A conspiracy theory is a belief that a group of people are secretly trying to harm someone or achieve something. You usually use this term to suggest that you think this is unlikely .
corpuscular theory
the theory, originally proposed by Newton , and revived with the development of the quantum theory, that light consists of a stream of particles
Darwinian theory
Darwin's theory of evolution , which holds that all species of plants and animals developed from earlier forms by hereditary transmission of slight variations in successive generations , and that natural selection determines which forms will survive
electroweak theory
a gauge theory of the electromagnetic and weak interactions
information theory
a collection of mathematical theories, based on statistics , concerned with methods of coding , transmitting , storing, retrieving , and decoding information
probability theory
the mathematical study of probability
scientific theory
A theory is a formal idea or set of ideas that is intended to explain something.
superdense theory
a cosmological theory postulating that approximately 12 billion years ago all the matter of the universe , packed into a small superdense mass, was hurled in all directions by a cataclysmic explosion . As the fragments slowed down, the galaxies and stars evolved but the universe is still expanding
test a theory
If you have a theory about something, you have your own opinion about it which you cannot prove but which you think is true.
big bang theory
In astronomy , the big bang theory is a theory that suggests that the universe was created as a result of an extremely large explosion.
boo-hurrah theory
the theory that moral utterances do not have a truth value but express the feelings of the speaker , so that murder is wrong is equivalent to down with murder
disprove a theory
A theory is a formal idea or set of ideas that is intended to explain something.
James-Lange theory
a theory that emotions are caused by bodily sensations ; for example, we are sad because we weep
Chinese translation of 'theory'
theory
(ˈθɪərɪ)
n(c/u)
理论(論) (lǐlùn)
in theory就理论(論)而言 (jiù lǐlùn ér yán)
1 (noun)
Definition
a set of ideas, based on evidence and careful reasoning, which offers an explanation of how something works or why something happens, but has not been completely proved
He produced a theory about historical change.
Synonyms
hypothesis
Different hypotheses have been put forward.
philosophy
his philosophy of non-violence
system of ideas
plan
She met her creditors to propose a plan for making repayments.
system
the decimal system of metric weights and measures
science
scheme
a private pension scheme
proposal
the government's proposals to abolish free health care
principles
ideology
capitalist ideology
thesis
This thesis does not stand up to close inspection.
Opposites
fact
,
experience
,
practice
,
reality
,
certainty
2 (noun)
Definition
an idea or opinion
There is a theory that they met each other a few years ago.
Synonyms
belief
It is my belief that a common ground can be found.
feeling
She has strong feelings about the growth in violence.
speculation
I had published my speculations about the future of the universe.
assumption
They are wrong in their assumption that we are all alike.
guess
My guess is that she's waiting for you to make the first move.
hunch
presumption
the presumption that a defendant is innocent until proved guilty
conjecture
Your assertion is merely a conjecture, not a fact.
surmise
Her surmise proved correct.
supposition
There's a popular supposition that we're publicly funded.
phrase
See in theory
Additional synonyms
in the sense of assumption
Definition
something that is taken for granted
They are wrong in their assumption that we are all alike.
Synonyms
presumption,
theory,
opinion,
belief,
guess,
expectation,
fancy,
suspicion,
premise,
acceptance,
hypothesis,
anticipation,
inference,
conjecture,
surmise,
supposition,
presupposition,
premise,
postulation
in the sense of conjecture
Definition
a guess
Your assertion is merely a conjecture, not a fact.
Synonyms
guess,
theory,
fancy,
notion,
speculation,
assumption,
hypothesis,
inference,
presumption,
surmise,
theorizing,
guesswork,
supposition,
shot in the dark,
guesstimate (informal)
in the sense of feeling
Definition
opinion or view
She has strong feelings about the growth in violence.
Synonyms
opinion,
view,
attitude,
belief,
point of view,
instinct,
inclination
Synonyms of 'theory'
theory
Explore 'theory' in the dictionary
Additional synonyms
in the sense of guess
My guess is that she's waiting for you to make the first move.
Synonyms
supposition,
feeling,
idea,
theory,
notion,
suspicion,
hypothesis
in the sense of ideology
Definition
the body of ideas and beliefs of a person, group, or nation
capitalist ideology
Synonyms
belief(s),
ideas,
principles,
ideals,
opinion,
philosophy,
doctrine,
creed,
dogma,
tenets,
world view,
credence,
articles of faith,
Weltanschauung
in the sense of philosophy
Definition
a personal outlook or viewpoint
his philosophy of non-violence
Synonyms
outlook,
values,
principles,
convictions,
thinking,
beliefs,
doctrine,
ideology,
viewpoint,
tenets,
world view,
basic idea,
attitude to life,
Weltanschauung
in the sense of plan
Definition
a method thought out for doing or achieving something
She met her creditors to propose a plan for making repayments.
Synonyms
scheme,
system,
design,
idea,
programme,
project,
proposal,
strategy,
method,
suggestion,
procedure,
plot,
device,
scenario,
proposition,
contrivance
in the sense of presumption
Definition
a belief or assumption based on reasonable evidence
the presumption that a defendant is innocent until proved guilty
Synonyms
assumption,
opinion,
belief,
guess,
hypothesis,
anticipation,
conjecture,
surmise,
supposition,
presupposition,
premise
in the sense of proposal
Definition
a suggestion put forward for consideration
the government's proposals to abolish free health care
Synonyms
suggestion,
plan,
programme,
scheme,
offer,
terms,
design,
project,
bid,
motion,
recommendation,
tender,
presentation,
proposition,
overture,
proffer
in the sense of scheme
Definition
a systematic plan for a course of action
a private pension scheme
Synonyms
plan,
programme,
strategy,
system,
design,
project,
theory,
proposal,
device,
tactics,
course of action,
contrivance
in the sense of speculation
I had published my speculations about the future of the universe.
Synonyms
theory,
opinion,
hypothesis,
conjecture,
guess,
consideration,
deliberation,
contemplation,
surmise,
guesswork,
supposition
in the sense of supposition
Definition
an idea or a statement believed or assumed to be true
There's a popular supposition that we're publicly funded.
Synonyms
belief,
idea,
notion,
view,
theory,
speculation,
assumption,
hypothesis,
presumption,
conjecture,
postulate,
surmise,
guesswork,
guess
in the sense of surmise
Definition
a conclusion based on incomplete or uncertain evidence
Her surmise proved correct.
Synonyms
guess,
speculation,
assumption,
thought,
idea,
conclusion,
notion,
suspicion,
hypothesis,
deduction,
inference,
presumption,
conjecture,
supposition
Additional synonyms
in the sense of system
Definition
a method or set of methods for doing or organizing something
the decimal system of metric weights and measures
Synonyms
method,
practice,
technique,
procedure,
routine,
theory,
usage,
methodology,
frame of reference,
modus operandi,
fixed order
in the sense of thesis
Definition
an opinion supported by reasoned argument
This thesis does not stand up to close inspection.