Ranked by relevance and common usage.
Keep "rarefy" when the sentence already sounds natural, when a synonym would add unintended emphasis, or when readers need the most familiar wording. A synonym should clarify or sharpen the message, not simply make the sentence look more varied.
If two options seem close, choose the one that best matches the audience and purpose of the sentence.
Choose a synonym only if it keeps the core idea of "rarefy" intact in the sentence you are editing.
Check whether the replacement sounds more formal, casual, emotional, technical, or forceful than the original word.
Read the full sentence after the swap. Keep the synonym only when the sentence becomes clearer or more precise.
Review note: Synonym lists are ranked with lexical data and reviewed for practical writing value. Use the comparison notes, sentence evidence, and source labels together; a high-ranking synonym can still be wrong when the audience, register, or grammar changes.
After choosing a replacement for "rarefy", read the sentence once for meaning and once for rhythm. The best synonym should feel natural in the full sentence, not only accurate in a word list.
If the synonym makes the sentence slower, vaguer, or more dramatic than intended, keep "rarefy" or choose a simpler alternative from the closest-match group.
OpenGloss and ConceptNet supply richer edges like generalizations, collocations, and derivations.
12 translations across 5 languages.
4 total sentences available.
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[…]
Source: wiktionary
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[…]
Source: wiktionary
As water rarefies, it evaporates, forming visible steam, and this may be a step toward the final category of reality, fire. Anyone who has held a hand over a boiling kettle may feel the truth of this.[…]
Source: wiktionary
Given the high quantity of water molecules in the human body it is worthy of note at this point that moisture rarefies when heated.[…]
Source: wiktionary
Closest matches include attenuate, add to, adulterate, aggrandize, amplify.
Compare the replacement against real sentence context. This entry includes sample sentences so you can check tone, grammar, and meaning before swapping words.