English · Science & Technology
theory
/ˈθɪə.ri/
[/ˈθɪə.ri/]
explained system of ideas
Intermediatenoun
Definition
A well-supported explanation of how or why something happens, based on repeated evidence.
Example
The theory of evolution explains how living species have changed gradually over millions of years.
The theory of evolution explains how living species have changed gradually over millions of years.
Etymology
From Greek 'theoria' (contemplation, speculation), from 'theorein' (to look at), via Late Latin.
How & Where It’s Used
In science, a theory is well-tested, unlike the casual 'just a theory' sense.