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 list goes on… CT joins 19-state effort against Trump opposition to offshore wind energy Trump has moved to shut down renewable energy, particularly offshore wind, as expensive and unreliable, while supporting expansion of fossil fuel development. —Dr. Jonathan Rosen, Hartford Courant, 11 May 2025

The explosions in Amritsar - the first heard there in the three-day-old conflict between the nuclear-armed neighbors - could mark a further expansion in the hostilities that have alarmed world powers. —USA Today, 11 May 2025

New York’s expansive use of eminent domain needed and still needs reining in, not expansion. —New York Daily News Editorial Board, New York Daily News, 11 May 2025

The expansion of human populations into the wildland-urban interface further fragments bear habitats, displacing the animals and forcing them into closer contact with humans. —Benjamin Alva Polley, Rolling Stone, 10 May 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