|Origin:||theoria, from Greek, from theorein 'to look at'|
an idea or set of ideas that is intended to explain something about life or the world, especially an idea that has not yet been proved to be true [↪ theoretical]
different theories about how the brain works
Darwin's theory of evolution
the theory that light is made up of waves
general principles and ideas about a subject:
Freudian theory has had a great influence on psychology.
political/economic/literary etc theory
I'm taking a course on political theory.
something that is true in theory is supposed to be true, but might not really be true or might not be what will really happen:
In theory, everyone will have to pay the new tax.
an idea or opinion that someone thinks is true but for which they have no proof
Detectives are working on a theory that he knew his murderer.