theory
theory
noun
OPAL W OPAL S
/ˈθɪəri/
(plural theories)
1 countable, uncountable a formal set of ideas that is intended to explain why something happens or exists
theory of something the theory of evolution/relativity
scientific/economic theory
The theories were tested on a sample of the population.
theory about something He developed a new theory about the cause of stomach ulcers.
theory on something theories on human behaviour
theory behind something She has written a book explaining the theory behind her art.
according to a theory According to the theory of relativity, nothing can travel faster than light.
Collocations Scientific research
SEE ALSO atomic theory, binding theory, catastrophe theory, chaos theory, critical theory, decision theory, game theory, government and binding theory, grand unified theory, information theory, quantum theory
TOPICS Scientific research B1
Collocations
adjective
completeunifiedgeneral…
… of theories
set
verb + theory
haveholdadvance…
theory + verb
hold somethingsuggest somethingexplain something…
preposition
in theorytheory about
phrases
put (the) theory into practicetheory and practice
2 uncountable the principles on which a particular subject is based
the theory and practice of language teaching
This is your chance to put theory into practice .
literary theory
3 countable an opinion or idea that somebody believes is true but that is not proved
theory about something Theories abound (= people have lots of different ideas) about what happened.
theory on something Here's my theory on how the story's going to end.
theory that… I don't subscribe to the theory that all Hollywood audiences want a happy ending.
Police are working on the theory that the murderer was known to the family.
SEE ALSO conspiracy theory
TOPICS Opinion and argument B1
Idioms
in theory
Word Origin
late 16th cent. (denoting a mental scheme of something to be done): via late Latin from Greek theōria ‘contemplation, speculation’, from theōros ‘spectator’.