What does "rarefy" mean?
To make rare, thin, porous, or less dense.
verb ·Moderate ·College level
This entry combines structured lexical data with WordToolSet review checks. Definitions, examples, synonyms, and usage notes may come from different source tables, so the page is designed to show evidence from more than one angle before you rely on "rarefy" in a final draft.
If a word has several senses, prefer the sense that matches your sentence's grammar and surrounding context. A correct definition can still be the wrong choice when the sentence needs a different register, emphasis, or level of specificity.
Read the first definition as a starting point, then check the example, synonyms, and part of speech before treating "rarefy" as the right word for your sentence.
If your draft is formal, technical, persuasive, or sensitive, compare "rarefy" with a nearby alternative so the final choice matches both meaning and reader expectation.
Check whether "rarefy" is acting as verb in your sentence. A definition is only useful when the grammar matches the way the word is being used.
Compare it with "attenuate" and other nearby choices to see whether the sentence needs a softer, stronger, or more familiar word.
Use the example sentence below as an evidence check, then read your own sentence out loud to catch tone or rhythm problems.
Review note: Definition pages are checked for source coverage, sentence evidence, synonym support, and editorial insight before they are treated as approval-ready pages. If the evidence is too thin, the page remains available to users but is kept out of the approval-facing indexed inventory.
Before publishing a sentence with "rarefy", ask whether the word helps the reader understand the idea faster. A precise word should reduce confusion, not simply make the sentence look more polished.
When the definition, synonym evidence, and example context point in the same direction, the word is usually a safer choice. When they conflict, revise the sentence or choose a clearer alternative.
"By means of this gauge, Mr. Smeaton judged that his machine was incomparably better than any former one, as it seemed to rarefy the air in the receiver 1000, or even 2000 times, while the best of these only rarefied it about 140[…]"
"For if The^([sic]) water rarefies and then Condenses, all that great mass of water of the Lake of the Ilinois rises in its vast basin when it rarefies, and falls when it condenses. And, as water always rises as much as it falls, it would[…]"
"By means of this gauge, Mr. Smeaton judged that his machine was incomparably better than any former one, as it seemed to rarefy the air in the receiver 1000, or even 2000 times, while the best of these only rarefied it about 140[…]"
To make rare, thin, porous, or less dense.
Common synonyms include: attenuate, add to, adulterate, aggrandize, amplify, attenuate.
By means of this gauge, Mr. Smeaton judged that his machine was incomparably better than any former one, as it seemed to rarefy the air in the receiver 1000, or even 2000 times, while the best of these only rarefied it about 140[…]
Pronounced /ˈɹɛəɹəˌfaɪ/.
From Middle English rarefien, from Old French rarefier (French raréfier), from Latin rarefacere (“make rare”). By surface analysis, rare + -fy.