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# theory

«theory» in Mova's school dictionary: **a well-tested explanation of how something in nature…** — its meaning for a pupil, its sense in the lessons and examples, with 2 sentences of Mova's corpora that use it.

### part of speech

noun (a theory, theories; theory — uncountable)

### meaning for a pupil

1) (science) A theory is a well-tested explanation of how something in nature works, supported by a lot of evidence, like the theory of evolution or the theory of gravity. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/T/theory/#m1)

2) A theory is an idea someone has to explain something, which may or may not be true, as in "I have a theory about who ate the cake". [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/T/theory/#m2)

3) Theory is the ideas and rules of a subject, as opposed to practice, like music theory. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/T/theory/#m3)

4) "In theory" means what should happen if things go as planned, though they might not. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/T/theory/#m4)

### sense in the lessons

In science lessons, pupils learn that a scientific theory is not just a guess: it has been tested many times. In stories, a detective forms a theory about the crime. In music lessons, theory means notes, scales and rhythm rules. Phrases: "in theory", "come up with a theory", "test a theory", "theory and practice", "conspiracy theory".

### examples

- Darwin's theory of evolution explains how living things change over time. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/T/theory/#x1)
- I have a theory that the cat ate the fish fingers. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/T/theory/#x2)
- In theory, the bus comes every ten minutes, but it never does. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/T/theory/#x3)
- The detective tested her theory by checking the footprints. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/T/theory/#x4)
- I passed my music theory exam. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/T/theory/#x5)
- Scientists test a theory by doing experiments. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/T/theory/#x6)
- (informal) Some people believe in silly conspiracy theories. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/T/theory/#x7)
- "I am not prepared to form a theory about these stories. [tree →](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/T/theory/#x8)

### note

Plural: theories (y → ies). Adjective: theoretical. A common trap: in everyday talk "just a theory" means a guess, but in science a theory is a strong, tested explanation. A "hypothesis" is the smaller idea you test in an experiment.

### In the corpora

- [A chihuahua and a Great Dane are the same species and could in theory have puppies together.](https://md.mova.elamur.ai/free/en/corpora/school/biology/192-dogs-from-wolves-to-hundreds-of-breeds/7/)
- [Before germ theory, many people believed illness came from bad air, called miasma.](https://md.mova.elamur.ai/free/en/corpora/school/medicine/30-germs-the-immune-system-and-hand-washing/16/)

### Trees and pragmatics

[Every meaning and example of «theory» parsed by Mova](https://md.mova.elamur.ai/free/en/corpora/dictionaries/school/T/theory/), each sentence with its dependency tree and frames.