theory
/ˈθɪə.ri/ IELTSAcademic
noun
- 1.
An idea or explanation that tries to describe how something works or why something happens. It is often based on evidence, but it may not be fully proven.
- Scientists tested the theory carefully.
- Her theory explains the sudden change.
- That is only a theory for now.
- 2.
A set of ideas used as a base for understanding a subject, especially in study or science.
- We studied language theory in class.
- The course covers basic economic theory.
- Her work combines theory and practice.
Adinary Nuance
Theory is not the same as fact. It is an explanation that tries to make sense of evidence, so it can change when new evidence appears. It is also more specific than idea or guess: a theory is usually better supported and more developed. In academic writing, theory can mean a formal system of ideas, not just one possible answer.
In other languages
- Vietnamese
- Lý thuyết
- Spanish
- Teoría
- Chinese
- 理论
- Japanese
- 理論
- Korean
- 이론
Etymology
The word comes from Greek theoria, meaning “looking at” or “contemplation.” It entered English through Latin and French in the Middle Ages.
Common phrases
a working theorytheory and practicescientific theoryjust a theory
Synonyms
Related words
Frequently asked questions
- Is theory a fact or an opinion?
- A theory is an explanation based on evidence. It is stronger than an opinion, but it may still change.
- What is the difference between theory and hypothesis?
- A hypothesis is a possible idea to test. A theory is usually broader and better supported by evidence.
- Can I say 'just a theory'?
- Yes, but it can sound dismissive. It means the idea is not proven yet.
- Is theory common in academic writing?
- Yes. It is very common in science, research, and university writing.