theory · noun /ˈθɪr.i/
Word family
Nouns: theory
Adjectives: theoretical
Verbs: theorize
Adverbs: theoretically
theory (IDEA)
B2 C an idea or set of ideas that is intended to explain something
Dictionary examples:
Darwin's theory of evolution
He has a theory that the hole was caused by a meteorite.
Learner example:
During his full time schedule, he worked [o]n his project about "relative theory". (First Certificate in English; B2; Farsi)
in theory
B2 If something is possible in theory, it should be possible, but often it does not happen in that way.
Dictionary example:
In theory, the trip ought to take three hours, but in practice it usually takes four because of road work.
Learner example:
To sum up, in theory you can find a lot of solutions [to] this problem, but in practi[c]e, actually some people who hunt without permission [aren't] punished. (First Certificate in English; B2; Catalan)
theory (PRINCIPLES)
C2 U the set of principles on which a subject is based
Dictionary example:
economic theory
Learner example:
Only after a few decades of further research did it become clear how many possible applications game theory actually has. (Certificate of Proficiency in English; C2; German)
