Learn the meaning, pronunciation and usage of the word expansion in English. Find out how to use it in different contexts, such as business, education and economy, with example sentences and synonyms. Expansion is the act or process of increasing in size, volume, or quantity, or the state of being expanded. It can also refer to a mathematical expression written in an extended form, or an increase in economic or business activity. The meaning of EXPANSION is expanse. How to use expansion in a sentence. Learn the meaning of expansion as a noun, with examples of different types of expansion , such as territorial, economic, and written. Find out how to use expansion in a sentence with Britannica Dictionary.