expansion

An act, process, or instance of expanding.

"The expansion of metals and plastics in response to heat is well understood."

The fractional change in unit length per unit length per unit temperature change.

"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."

A new addition.

"My new office is in the expansion behind the main building."

A product to be used with a previous product.

"This expansion requires the original game board."

That which is expanded; expanse; extended surface.

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.

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.

"Expansion of acronyms is often helpful for nonexpert readers (anacronyms excluded)."

The string of text thus substituted.

"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."

Ellipsis of expansion pack.

An increase in the market value of an economy over time.

Stretching of geometric objects with flat sides.

The rewriting of an expression as a longer but equivalent sum of terms.