Meaning & use
theory
A well-supported explanation of some aspect of the natural world, based on tested evidence.
See it in a sentence
Darwin's theory of evolution reshaped how scientists understand living species.
She had her own theory about why the meeting had been canceled.
A note on using this word
In casual speech "theory" often means a guess, but in science it denotes a rigorously tested explanation.
Words with a similar meaning
hypothesisexplanation
Choose a synonym to suit the sentence. Meanings can overlap without being identical.
Make it your own
Write a sentence using “theory”, then compare your use with the examples above.
Your draft stays on this page and is not sent anywhere.