Medical Definition expansion noun ex· pan· sion ik-ˈspan-chən 1 : the act or process of expanding

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.

EXPANSION definition: 1. the increase of something in size, number, or importance: 2. the increase of something in size…. Learn more.

Define expansion. expansion synonyms, expansion pronunciation, expansion translation, English dictionary definition of expansion. n. 1. a. The act or process of expanding: the new nation's …

Expansion is the part of an engine cycle in which the fluid increases in volume and makes a part such as a piston or flywheel move. The expansion of the gas pushes the piston inside the cylinder. The …

Definition of expansion noun in Oxford Advanced Learner's Dictionary. Meaning, pronunciation, picture, example sentences, grammar, usage notes, synonyms and more.

WordNet-Online dictionary. Definition, thesaurus and related words for 'expension'. Synonyms, antonyms, hypernyms, hyponyms, meronyms, usage examples, and much more...

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.

Oct 31, 2025 · Borrowed from French expansion, from Latin expānsiō. By surface analysis, expand +‎ -sion.

There are 14 meanings listed in OED's entry for the noun expansion, two of which are labelled obsolete. See ‘Meaning & use’ for definitions, usage, and quotation evidence.