# rarefaction

> English word · Noun

## Definitions
1. A reduction in the density of a material, especially that of a fluid.

## Etymology
From Middle French raréfaction. By surface analysis, rarefy + -faction.

## Source
Compiled from Wiktionary via kaikki.org (CC BY-SA). Data vintage: 2026-05-06.
Canonical page: https://plainspell.com/en/word/rarefaction