rarefaction

American  

[rair-uh-fak-shuhn] / ˌrɛər əˈfæk ʃən /

noun

1. the act or process of rarefying.

2. the state of being rarefied.

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rarefaction British  

/ ˌrɛərɪfɪˈkeɪʃən, ˌrɛərɪˈfækʃən /

noun

1. the act or process of making less dense or the state of being less dense

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rarefaction Scientific  

/ râr′ə-făk′shən /

1. A decrease in density and pressure in a medium, such as air, especially when caused by the passage of a wave, such as a sound wave.

2. The region in which this occurs.

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Other Word Forms

• rarefactional adjective
• rarefactive adjective

Etymology

Origin of rarefaction

1595–1605; < Medieval Latin rārēfactiōn- (stem of rārēfactiō ), equivalent to Latin rārēfact ( us ) (past participle of rārēfacere; see rarefy) + -iōn- -ion

Explanation

A decrease in the density of something is rarefaction. As you climb a mountain, you experience rarefaction of the air; the air becomes less dense the higher up you go. Most of the time, rarefaction refers to air or other gases becoming less dense. When rarefaction occurs, the particles in a gas become more spread out. You may come across this word in the context of sound waves. A sound wave moving through air is made up of alternating areas of higher and lower density. The areas of lower density are called rarefactions.

Example Sentences

In untreated fish, one of the most striking signs of kidney decline was the gradual loss of capillaries, a process known as vascular rarefaction.

From Science Daily • Jan. 30, 2026

The results from both of these null models were qualitatively consistent, so we only report findings using the equiprobable rows, fixed columns model, as it is more consistent with rarefaction of the observation tables.

From Nature • Oct. 31, 2017

Figure 17.4 As the string moves to the left, it creates another compression and rarefaction as the ones on the right move away from the string.

From Textbooks • Aug. 12, 2015

This is how noise-canceling headphones work—they produce a sound wave that resembles the wave responsible for the unwanted sound, but with the original phases of rarefaction and compression flipped.

From Scientific American • Dec. 12, 2013

The air may be rendered dielectrically weak also by rarefaction.

From The inventions, researches and writings of Nikola Tesla With special reference to his work in polyphase currents and high potential lighting by Martin, Thomas Commerford

Related Words

• gap
• void