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 expansion of the child tax credit in the House and Senate versions of the bill is less than many pro-family conservatives would have liked. —Zach Halaschak, The Washington Examiner, 16 June 2025

The news marks the first international expansion for Jackson’s FAST network. —Jesse Whittock, Deadline, 16 June 2025

As luck would have it, the expansion Tampa Bay Devil Rays, as they were then known, were to begin play in 1998 and commence minor league and player development operations in 1997, a year after Militello threw his final pitch. —Tom Layberger, Forbes.com, 16 June 2025

The expansion of Medicaid services means that tribal clinic service providers in the affected states are better equipped to deliver care in areas other than their clinics, such as remote residential areas. —Theo Burman, MSNBC Newsweek, 15 June 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