expansion

American  

[ik-span-shuhn] / ɪkˈspæn ʃən /

noun

1. the act or process of expanding.

2. the state or quality of being expanded.

3. the amount or degree of expanding.

4. an expanded, dilated, or enlarged portion or form of a thing.

   The present article is an expansion of one he wrote last year.

5. anything spread out; expanse.

6. Mathematics.

   1. the development at length of an expression indicated in a contracted form, as a 2 + 2 ab + b 2 for the expression (a +b ) 2 .

   2. any mathematical series that converges to a function for specified values in the domain of the function, as 1 + x + x 2 + … for 1/(1 −x ) when x < 1.

7. Machinery. that part of the operation of an engine in which the volume of the working medium increases and its pressure decreases.

8. an increase in economic and industrial activity (opposed to contraction).

9. additional content for a video game, card game, board game, etc., that significantly expands or alters the way the game is played.

   I really improved my deck with cards from the latest expansion.

   You can play the stand-alone expansion without ever buying the original game.

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expansion British  

/ ɪkˈspænʃən /

noun

1. the act of expanding or the state of being expanded

2. something expanded; an expanded surface or part

3. the degree, extent, or amount by which something expands

4. an increase, enlargement, or development, esp in the activities of a company

5. maths

   1. the form of an expression or function when it is written as the sum or product of its terms

   2. the act or process of determining this expanded form

6. the part of an engine cycle in which the working fluid does useful work by increasing in volume

7. the increase in the dimensions of a body or substance when subjected to an increase in temperature, internal pressure, etc

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expansion Scientific  

/ ĭk-spăn′shən /

1. An increase in the volume of a substance while its mass remains the same. Expansion is usually due to heating. When substances are heated, the molecular bonds between their particles are weakened, and the particles move faster, causing the substance to expand.

2. A number or other mathematical expression written in an extended form. For example, a ² + 2 ab + b ² is the expansion of (a + b) ².

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Other Word Forms

• antiexpansion adjective
• expansional adjective
• expansionary adjective
• nonexpansion noun
• overexpansion noun
• preexpansion noun
• reexpansion noun
• self-expansion noun
• superexpansion noun

Etymology

Origin of expansion

First recorded in 1605–15; from Late Latin expānsiōn-, stem of expānsiō; equivalent to expanse + -ion

Explanation

Expansion is what happens when something becomes bigger or more extensive. If you enjoy good pastry, you will be excited by the expansion of the bakery, but be careful or you will also see the expansion of your waistline. The noun expansion is from the Latin word expansionem, which means a spreading out. Another definition for expansion is an elaboration or expanding upon something. If you're a teacher, you might be asked to give an expansion of the short talk you give students, "Homework Stinks: But Why We Need It Anyway" to parents at the school open house.

Example Sentences

What is the outlook for gross margin expansion?

From Barron's • Apr. 30, 2026

Her priorities have included early education expansion, school greening improvements, literacy through phonics training, protecting immigrant students and focusing more budget resources on the highest-need schools.

From Los Angeles Times • Apr. 30, 2026

CVS doesn’t need a lot of multiple expansion for the stock to go up.

From Barron's • Apr. 30, 2026

The Chinese thin-film deposition equipment provider is poised to benefit from a strong memory expansion upcycle, the analysts say.

From The Wall Street Journal • Apr. 29, 2026

Over the course of the next four decades, the national debate over slavery and its expansion into the West was often framed as an argument over the intent of the founders.

From "Founding Brothers: The Revolutionary Generation" by Joseph J. Ellis

Related Words

• development
• enlargement
• extension
• increase
• inflation
• spread