ex·​pan·​sion | \ ik-ˈspan(t)-shən How to pronounce expansion (audio) \

Definition of expansion

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
5a : 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

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Other Words from expansion

expansional \ ik-​ˈspanch-​nəl How to pronounce expansional (audio) , -​ˈspan(t)-​shə-​nᵊl \ adjective

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.
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Recent Examples on the Web

The two sides would most likely meet in the middle, meaning a massive expansion of Medicare. Flaviu Simihaian, Fortune, "Private Insurers Are Afraid of Medicare for All. They Should Be Excited," 5 June 2019 First Watch arrived in Dania Beach in January, part of a rapid South Florida expansion for the national chain, and boutique chain Yolk from Chicago arrived in Boca Raton in February. Michael Mayo, sun-sentinel.com, "All-day breakfast: A critic’s guide to 5 egg-centric new eateries," 5 June 2019 But after a few expansions and a lot of patches, the game was able to attract an impressive 30 million sales by 2015. Kyle Orland, Ars Technica, "Did Fallout 76 launch too early or just in time to be saved?," 4 June 2019 To pull off a fluctuation like YIHO would require a radical expansion of subjective time under an altered state of consciousness. Josh Wilbur, WIRED, "You Could Live Forever With This Sci-Fi Time Hack," 4 June 2019 For example, Harrah's Ak-Chin Casino near Maricopa recently announced a major expansion and remodel phase on its 25th anniversary. Russ Wiles, azcentral, "Arizona Lottery exceeds $1 billion in sales for first time ever," 4 June 2019 The Fed has raised rates four times since Mr. Trump named Jerome Powell chairman to keep a decade-long economic expansion from overheating and crashing the economy. Rachel Layne, CBS News, "As more tariffs loom, experts warn consumers to brace for impact," 3 June 2019 Originally, the brand launched the line in just 250 locations, but after a mere six months of mega-success, the retailer requested a chain-wide expansion due to such high demand. Kaleigh Fasanella, Allure, "You Can Now Shop Peach & Lily Skin-Care Products at Ulta Stores," 29 Mar. 2019 Spanning four floors, the new space will be a major expansion from its current one-room location. Christian Allaire, Vogue, "Touring Germany’s Most Festive Christmas Markets," 18 Dec. 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'expansion.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of expansion

1611, in the meaning defined at sense 1

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Statistics for expansion

Last Updated

9 Jun 2019

Look-up Popularity

Time Traveler for expansion

The first known use of expansion was in 1611

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More Definitions for expansion



English Language Learners Definition of expansion

: the act of becoming bigger or of making something bigger : the act of expanding
: a more complete and detailed written work or set of comments based on something shorter


ex·​pan·​sion | \ ik-ˈspan-shən How to pronounce expansion (audio) \

Kids Definition of expansion

: the act of growing or increasing : enlargement


ex·​pan·​sion | \ ik-ˈspan-chən How to pronounce expansion (audio) \

Medical Definition of expansion

1 : the act or process of expanding
2 : the quality or state of being expanded

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Comments on expansion

What made you want to look up expansion? Please tell us where you read or heard it (including the quote, if possible).


to move with exaggerated bouncy motions

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