noun · 16 senses · updated from the 2026-07-25 local source snapshot
Definitions and examples are grouped by meaning. Pronunciation, history, word forms, translations, descendants, synonyms, antonyms, derived terms, and related words appear whenever the source provides them.
Sound
Pronunciation
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/ɪkˈspænʃən/
US:Recorded audio is listed in the source snapshot.
CMU ARPABET:IH0 K S P AE1 N SH AH0 N
Digits mark lexical stress: 1 primary, 2 secondary, 0 unstressed.
CMU ARPABET 2:IH0 K S P AE1 N CH AH0 N
Digits mark lexical stress: 1 primary, 2 secondary, 0 unstressed.
1
noun
Meaning 1
An act, process, or instance of expanding.
Definition source: English Wiktionary via Wiktextract
Usage: countable, uncountable
Examples
The expansion of metals and plastics in response to heat is well understood.
Meaning relationships
Synonyms: none provided
Antonyms: none provided
2
noun
Meaning 2
An act, process, or instance of expanding.
The fractional change in unit length per unit length per unit temperature change.
Definition source: English Wiktionary via Wiktextract
Usage: countable, uncountable
Examples
Look up the expansion of 1018 steel at stick welding temps and figure out how far this thing's gonna bend once we weld it up.
Meaning relationships
Synonyms: coefficient of thermal expansion
Antonyms: none provided
Broader terms: temperature coefficient
3
noun
Meaning 3
An act, process, or instance of expanding.
A new addition.
Definition source: English Wiktionary via Wiktextract
Usage: countable, uncountable
Qualifier: building
Examples
My new office is in the expansion behind the main building.
Meaning relationships
Synonyms: annex
Antonyms: none provided
4
noun
Meaning 4
An act, process, or instance of expanding.
A product to be used with a previous product.
Definition source: English Wiktionary via Wiktextract
Usage: countable, uncountable
Examples
This expansion requires the original game board.
Meaning relationships
Synonyms: none provided
Antonyms: none provided
5
noun
Meaning 5
An act, process, or instance of expanding.
That which is expanded; expanse; extended surface.
Definition source: English Wiktionary via Wiktextract
Usage: countable, uncountable
No example sentence was provided for this meaning.
Meaning relationships
Synonyms: none provided
Antonyms: none provided
6
noun
Meaning 6
An act, process, or instance of expanding.
The operation of steam in a cylinder after its communication with the boiler has been cut off, by which it continues to exert pressure upon the moving piston.
Definition source: English Wiktionary via Wiktextract
Usage: countable, uncountable
Qualifier: steam engines
No example sentence was provided for this meaning.
Meaning relationships
Synonyms: none provided
Antonyms: none provided
7
noun
Meaning 7
An act, process, or instance of expanding.
The replacement of a short name (e.g., acronym, initialism, alphanumeric symbol, abbreviation) with the longer name that is synonymous with it, as when spelling out acronyms to ensure clarity for a general audience.
Definition source: English Wiktionary via Wiktextract
Usage: countable, uncountable
Examples
Expansion of acronyms is often helpful for nonexpert readers (anacronyms excluded).
Meaning relationships
Synonyms: none provided
Antonyms: none provided
8
noun
Meaning 8
An act, process, or instance of expanding.
The replacement of a short name (e.g., acronym, initialism, alphanumeric symbol, abbreviation) with the longer name that is synonymous with it, as when spelling out acronyms to ensure clarity for a general audience.
The string of text thus substituted.
Definition source: English Wiktionary via Wiktextract
Usage: countable, uncountable
Examples
The acronym "FNDs" can mean either "functional neurologic disorders" or "focal neurologic deficits", so you'd better use the expansion instead of the acronym, for clarity in this context; readers of this paragraph may not have read, or remember, which definition you used 40 pages earlier.
Meaning relationships
Synonyms: none provided
Antonyms: none provided
9
noun
Meaning 9
An act, process, or instance of expanding.
Ellipsis of expansion pack.
Definition source: English Wiktionary via Wiktextract