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.
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
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.
used to say that a particular statement is supposed to be true but may in fact be wrong
In theory, these machines should last for ten years or more.
That sounds fine in theory, but have you really thought it through?
‘Aren’t you supposed to be retired?’ ‘Yes, in theory.’
In theory, all children get an equal chance at school.
