- the act of expanding or the state of being expanded
- something expanded; an expanded surface or part
- the degree, extent, or amount by which something expands
- an increase, enlargement, or development, esp in the activities of a company
- the increase in the dimensions of a body or substance when subjected to an increase in temperature, internal pressure, etc
WordReference Random House Learner's Dictionary of American English © 2026
ex•pan•sion /ɪkˈspænʃən/USA pronunciation
n.
WordReference Random House Unabridged Dictionary of American English © 2026- the act or process of expanding;
the state or quality of being expanded:[uncountable]Future expansion of the business will require us to build more factories. The runway is undergoing expansion to allow bigger planes to land there. - [countable] an expanded portion or form of a thing: The book is an expansion of a series of articles.
ex•pan•sion
(ik span′shən),USA pronunciation n.
ex•pan′sion•al, adj.
- the act or process of expanding.
- the state or quality of being expanded.
- the amount or degree of expanding.
- an expanded, dilated, or enlarged portion or form of a thing:The present article is an expansion of one he wrote last year.
- anything spread out;
expanse. - Mathematics
- the development at length of an expression indicated in a contracted form, as a2 + 2ab + b2 for the expression (a + b)2.
- Mathematicsany mathematical series that converges to a function for specified values in the domain of the function, as 1 + x + x2 + … for 1/(1 - x) when x
1.
- Mechanical Engineering[Mach.]that part of the operation of an engine in which the volume of the working medium increases and its pressure decreases.
- Communications, Businessan increase in economic and industrial activity (opposed to contraction).
- Late Latin expānsiōn- (stem of expānsiō) a spreading out. See expanse, -ion
- 1605–15
Collins Concise English Dictionary © HarperCollins Publishers::
expansion /ɪkˈspænʃən/ n
'expansion' also found in these entries (note: many are not synonyms or translations):
air engine
- bellows
- bimetallic strip
- binomial theorem
- bridgehead
- cadre
- coefficient of expansion
- critical density
- defroster
- diastole
- elastic
- expanse
- expansive
- expansivity
- explode
- gold reserve
- inflation
- inflationary universe
- inflationism
- Invar
- James I
- Japan
- John I
- John II
- John III
- Meiji
- Menelik II
- mushroom
- National Socialism
- oscillating universe theory
- protection
- pulsating star
- pulse
- Pyrex
- reaction turbine
- retina
- South Sea Bubble
- sponson
- sprawl
- spread
- stop-go
- swell
- swelling
- tamper
- thunder
- treatment
- vesicle
- whip
- abridgment
- adapter