rarefy

verb

rar·​e·​fy ˈrer-ə-ˌfī How to pronounce rarefy (audio)
variants or less commonly rarify
rarefied; rarefying

transitive verb

1
: to make rare, thin, porous, or less dense : to expand without the addition of matter
2
: to make more spiritual, refined, or abstruse

intransitive verb

: to become less dense

Examples of rarefy in a Sentence

Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
As rarefied as his work was, as an individual and as a spirit there was something to celebrate — and yet there were foibles and missteps along the way too, so there was real good drama there. — Tim Greiving, latimes.com, 3 June 2019 But in 2003, when Clear was founded, biometric technology was rarefied, known to the public mostly through science fiction films. — Claire Martin, New York Times, 8 Sep. 2017

Word History

Etymology

Middle English rarefien, rarifien, modification of Latin rarefacere, from rarus rare + facere to make — more at do

First Known Use

14th century, in the meaning defined at transitive sense 1

Time Traveler
The first known use of rarefy was in the 14th century

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Cite this Entry

“Rarefy.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/rarefy. Accessed 21 Mar. 2025.

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Kids Definition

rarefy

verb
rar·​efy
variants also rarify
ˈrar-ə-ˌfī,
ˈrer-
rarefied; rarefying
: to make or become rare, thin, or less dense

Medical Definition

rarefy

verb
rar·​e·​fy
variants also rarify
ˈrar-ə-ˌfī, ˈrer- How to pronounce rarefy (audio)
rarefied also rarified; rarefying also rarifying

transitive verb

: to make rare, thin, porous, or less dense : to expand without the addition of matter

intransitive verb

: to become less dense

More from Merriam-Webster on rarefy

Nglish: Translation of rarefy for Spanish Speakers

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