expansion

UK: /ɪkˈspænʃ^ən/ US: /ɪkˈspænʃən/ ,(ik span′shən)

WordReference Random House Learner's Dictionary of American English © 2025

ex•pan•sion /ɪkˈspænʃən/   n. 

1. 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.
2. [countable] an expanded portion or form of a thing:
   The book is an expansion of a series of articles.

See -pand-.

WordReference Random House Unabridged Dictionary of American English © 2025

ex•pan•sion  (ik span′shən), n. 

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
   • the development at length of an expression indicated in a contracted form, as a² + 2ab + b² for the expression (a + b)².
   • Mathematics any 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.
7. Mechanical Engineering [Mach.] that part of the operation of an engine in which the volume of the working medium increases and its pressure decreases.
8. Communications, Business an increase in economic and industrial activity (opposed to contraction).

• Late Latin expānsiōn- (stem of expānsiō) a spreading out. See expanse, -ion
• 1605–15

ex•pan′sion•al, adj. 

Collins Concise English Dictionary © HarperCollins Publishers::

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

exˈpansionary adjective