ex·​pan·​sion | \ik-ˈspan(t)-shən \

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 , -​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

Construction is underway for an expansion of Lou Malnati’s Pizzeria in Tinley Park that will create indoor dining space, a bar and private event room, according to the company. Mike Nolan, Daily Southtown, "Lou Malnati's in Tinley Park expanding," 13 July 2018 The Harry and Jeanette Weinberg Foundation is giving $120,000 over two years for expansion of the program. Andrea K. Mcdaniels, baltimoresun.com, "City expands telemedicine program for older adults in Park Heights," 12 July 2018 Due to concerns about costs and the need for so many classrooms, district architect STR Partners provided multiple options for Lincoln School’s expansion and renovation. Steve Schering, chicagotribune.com, "Parents focused on playground space, costs as Oak Park District 97 eyes Lincoln, Longfellow expansion plans," 11 July 2018 Aurora aldermen want to take a closer look at a plan to use ComEd poles for the expansion of the city’s fiber optic network. Steve Lord, Aurora Beacon-News, "Aurora council wants more study of using ComEd poles to expand fiber optic network," 11 July 2018 For example, the children in the business may want to leave cash and profits in the company for expansion or greater capitalization. Tom Cooney And Crystal Faulkner, Cincinnati.com, "Careful planning essential when transferring business ownership to children," 11 July 2018 And Nowaskie, who this month started at Indiana University School of Medicine as a resident in psychiatry, has plans for further expansion. Shari Rudavsky, Indianapolis Star, "These doctors may be in, but they're also friendly to patients who are out, website says," 7 July 2018 The restaurant closed in March at The Yard on Seventh Street, south of Montebello Avenue, allowing for the expansion of Fox's Culinary Dropout. Jennifer Mcclellan, azcentral, "Most shocking restaurant closings of the year in Phoenix ... so far," 5 July 2018 An additional 150,000 square feet is available for expansion of the Briggs & Stratton facility, according to Kreklow. Henry J. Morgan, Milwaukee Journal Sentinel, "Germantown OKs Briggs & Stratton development agreement; distribution center expected to be built by December 2019," 5 July 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

10 Nov 2018

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 \

Kids Definition of expansion

: the act of growing or increasing : enlargement


ex·​pan·​sion | \ik-ˈspan-chən \

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).


playful or foolish behavior

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