[Elamur Dictionary](https://md.dictionary.elamur.ai/free/en/) · [this page in HTML](https://dictionary.elamur.ai/free/en/english/theory/) [dictionaries](https://md.dictionary.elamur.ai/free/en/) / [English](https://md.dictionary.elamur.ai/free/en/english/) / [T](https://md.dictionary.elamur.ai/free/en/english/t/) / theory # theory noun (a theory, theories; theory — uncountable) «theory» in the English dictionary: everyday and in Jewish tradition — its meanings, how the lessons use it, and examples, each with its tree on Mova. ## Everyday 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://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://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://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://mova.elamur.ai/free/en/corpora/dictionaries/school/T/theory/#m4) ### 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://mova.elamur.ai/free/en/corpora/dictionaries/school/T/theory/#x1) - I have a theory that the cat ate the fish fingers. [tree →](https://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://mova.elamur.ai/free/en/corpora/dictionaries/school/T/theory/#x3) - The detective tested her theory by checking the footprints. [tree →](https://mova.elamur.ai/free/en/corpora/dictionaries/school/T/theory/#x4) - I passed my music theory exam. [tree →](https://mova.elamur.ai/free/en/corpora/dictionaries/school/T/theory/#x5) - Scientists test a theory by doing experiments. [tree →](https://mova.elamur.ai/free/en/corpora/dictionaries/school/T/theory/#x6) - (informal) Some people believe in silly conspiracy theories. [tree →](https://mova.elamur.ai/free/en/corpora/dictionaries/school/T/theory/#x7) - "I am not prepared to form a theory about these stories. [tree →](https://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 Jewish tradition 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 - Be this as it may, it is worth while to know the extravagant hypotheses which ancient Jewish philosophers and theologians framed as soon as they began to contemplate and to reason, endeavoring to combine oriental and Greek theories. (Sefer Yetzirah, Kalisch 1877) [tree →](https://mova.elamur.ai/free/en/corpora/dictionaries/judaism/T/theory/#x1) - The whole theory of the world, of the year, and of the soul, is expressed by tens and twelves. (Mordell, The Origin of Letters and Numerals according to Sefer Yetzirah (1914)) [tree →](https://mova.elamur.ai/free/en/corpora/dictionaries/judaism/T/theory/#x2) - Indeed, it would seem that every commentator endeavored to read his own views and theories into this little book, with hardly any concern whether they agreed with the text or not. (Mordell, The Origin of Letters and Numerals according to Sefer Yetzirah (1914)) [tree →](https://mova.elamur.ai/free/en/corpora/dictionaries/judaism/T/theory/#x3) ### 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. ## On Mova - [Trees and pragmatics of «theory» in the school dictionary](https://mova.elamur.ai/free/en/corpora/dictionaries/school/T/theory/): every meaning and example parsed by Mova, with its dependency tree and frames. - [«theory» in the school dictionary](https://mova.elamur.ai/free/en/dictionaries/school/w/theory.html) on Mova free. - [Trees and pragmatics of «theory» in the Judaism dictionary](https://mova.elamur.ai/free/en/corpora/dictionaries/judaism/T/theory/): every meaning and example parsed by Mova, with its dependency tree and frames. - [«theory» in the Judaism dictionary](https://mova.elamur.ai/free/en/dictionaries/judaism/w/theory.html) on Mova free.