expansion

noun

ex·​pan·​sion ik-ˈspan(t)-shən 

1

: expanse

2

: the act or process of expanding

territorial expansion

economic expansion

expansion of the universe

3

: the quality or state of being expanded

4

: the increase in volume of working fluid (such as steam) in an engine cylinder after cutoff or in an internal combustion engine after explosion

5

a

: an expanded part

b

: something that results from an act of expanding

the book is an expansion of a lecture series

6

: the result of carrying out an indicated mathematical operation : the expression of a function in the form of a series

expansional

ik-ˈspan(t)-sh(ə-)nəl 

adjective

Synonyms

• accretion
• accrual
• addendum
• addition
• augmentation
• boost
• gain
• increase
• increment
• more
• plus
• proliferation
• raise
• rise
• step-up
• supplement
• uptick

Examples of expansion in a Sentence

The league is undergoing expansion.

the expansion of a lecture series into a book

This book is an expansion of a lecture series.

Recent Examples on the Web

The centrepiece of this involved an expansion of the East Stand, adding 8,000 seats, which would be topped by a bubble-like roof. —Tom Burrows, The Athletic, 23 Mar. 2025

The new backstory between Peter (Alexander Molony) and Hook (Jude Law) represents the movie’s incomplete imagination, gesturing at an expansion of its source material without actually fleshing out those ideas. —Staff Author, EW.com, 22 Mar. 2025

For years, South Florida advocates have pushed for an expansion of the status, concerned that many Nicaraguans in the U.S. would be left with no other forms of relief from deportation if the parole program was revoked. —Jacqueline Charles, Miami Herald, 22 Mar. 2025

This would be a significant expansion to Musk's role in the government, and a potential conflict of interest. —Emily Forlini, PCMAG, 21 Mar. 2025

Word History

First Known Use

1611, in the meaning defined at sense 1

Phrases Containing expansion

• expansion card
• expansion slot

Rhymes for expansion

• mansion
• scansion

Kids Definition

expansion

noun

ex·​pan·​sion ik-ˈspan-chən 

1

: the act of expanding

2

: the state of being expanded

3

: something expanded or a result of expanding

4

: the result of carrying out indicated mathematical operations

the expansion of (a + b)² is a² + 2ab + b²

Medical Definition

expansion

noun

ex·​pan·​sion ik-ˈspan-chən 

1

: the act or process of expanding

2

: the quality or state of being expanded