Cambridge Dictionaries online Cambridge Dictionaries online

The most popular online dictionary and thesaurus for learners of English


English definition of “big bang theory”

big bang theory

noun [U]  /ˈbɪɡ ˈbæŋ ˌθɪər·i/
the very large explosion of a single mass of matter that many scientists believe was the beginning of the universe
(Definition of big bang theory noun from the Cambridge Academic Content Dictionary © Cambridge University Press)

Word of the Day


to pour liquid slowly over something, especially in a thin line or in small drops

Word of the Day


Read our blog about how the English language behaves.

Learn More

New Words

Find words and meanings that have just started to be used in English, and let us know what you think of them.

Learn More