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

Europe at that time was gripped by political questions concerning the place of women in society, free love, the expansion of the franchise, and the importance of scientific inquiry in civic life. Andrew Katzenstein, Harper's magazine, "The Radical Conservative," 16 Sep. 2019 The proposition would fund expansion of the police department’s public safety building as well cover costs to replace Fire Station No. 2’s building with a new station and training facility. Carissa D. Lamkahouan, Houston Chronicle, "Public safety facilities focus of Friendswood bond proposition," 16 Sep. 2019 The Navy in March authorized the expansion of its Growler program by up to three dozen jets, adding to the 82 already based on Whidbey Island, a 55-mile long island north of Seattle. Gene Johnson, The Seattle Times, "Whidbey Island residents sue Navy over Growler jet noise," 16 Sep. 2019 Democrats have expressed varying levels of willingness to negotiate with the White House - particularly on the expansion of background checks. The Washington Post, oregonlive, "White House readies gun plan, but Trump still conflicted," 14 Sep. 2019 Incoming European Commission president Ursula von der Leyen unveiled her team this week, including the expansion of responsibility for Margrethe Vestager. Fortune, "Female CEOs Up Their Activism: The Broadsheet," 13 Sep. 2019 Churchill Downs is seeking permission to permanently close a portion of Fourth Street to accommodate the expansion of its barn complex. Tim Sullivan, The Courier-Journal, "There's a horse racing boom in Kentucky. What's fueling it? Gaming machines," 13 Sep. 2019 Daikin America is planning a $195 million expansion of its Decatur plant, adding 50 new full-time positions over the next few years. William Thornton | Wthornton@al.com, al, "Decatur’s Daikin plans $195 million expansion, to create 50 jobs," 13 Sep. 2019 How Cleveland Clinic and Fairfax are reinventing their relationship for a brighter future: Many Fairfax residents have felt threatened and displaced by the Cleveland Clinic’s expansion of its main campus. Anne Nickoloff, cleveland.com, "FreshWater Cleveland’s Fairfax ‘On the Ground’ series: Education, food, innovation, more," 13 Sep. 2019

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

13 Oct 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 fake an opponent out of position

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