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
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
Meanwhile, many museums are in serious financial straits, reckoning with the fiscal burden of optimistic expansions and unanticipated increases in operating costs.
—
Katy Siegel, Artforum, 2 June 2026
Much of the space created in the 2013 expansion of the top two stories was devoted to wellness facilities (including a decent-sized pool, a rarity in Geneva hotels).
—Condé Nast, Condé Nast Traveler, 2 June 2026
Venus in Leo, on the other hand, dazzles your ninth house of expansion, supporting your travels, education and creative inspiration, while Jupiter entering Leo at the end of the month begins a larger cycle and chapter of growth.
—Valerie Mesa, PEOPLE, 1 June 2026
It is set to overcome the growing competition for available land, a great challenge in solar energy expansion.
—Georgina Jedikovska, Interesting Engineering, 1 June 2026
See All Example Sentences for expansion
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Katy Siegel, Artforum, 2 June 2026
Much of the space created in the 2013 expansion of the top two stories was devoted to wellness facilities (including a decent-sized pool, a rarity in Geneva hotels).
—Condé Nast, Condé Nast Traveler, 2 June 2026
Venus in Leo, on the other hand, dazzles your ninth house of expansion, supporting your travels, education and creative inspiration, while Jupiter entering Leo at the end of the month begins a larger cycle and chapter of growth.
—Valerie Mesa, PEOPLE, 1 June 2026
It is set to overcome the growing competition for available land, a great challenge in solar energy expansion.
—Georgina Jedikovska, Interesting Engineering, 1 June 2026
See All Example Sentences for expansion
Cite this Entry
“Expansion.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/expansion. Accessed 3 Jun. 2026.
Copy CitationKids 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
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