Etymograph

English

rarefaction

Rarefaction comes from Middle French raréfaction.

  1. Middle Frenchc. 1400–1600raréfaction1
  2. Englishearliest quotation 1663rarefaction1

attested reconstructed ? uncertain or disputed deepest recorded ancestor

  1. 1 Wiktionary, English rarefaction
  2. Earliest quotation in Wiktionary’s entry: 1663, Robert Boyle, Title I. Experiments Touching Bodies Capable of Freezing Oth: “[T]his ſeal'd vial, being broken under water, ſuck'd in…”.

Lineage

  1. Middle Frenchc. 1400–1600raréfactionWiktionary, English rarefaction
  2. Englishearliest quotation 1663rarefactionWiktionary, English rarefaction. Earliest quotation in Wiktionary’s entry: 1663, Robert Boyle, Title I. Experiments Touching Bodies Capable of Freezing Oth: “[T]his ſeal'd vial, being broken under water, ſuck'd in…”

Equivalent to rarefy + -faction

Latin rarefaciō ‘make rare’

Old French rarefier

Middle English rarefien ‘to reduce’

English rarefy

Every English word from Middle French raréfaction

Today it means

noun A reduction in the density of a material, especially that of a fluid.

Sources

Sources: Wiktionary, “rarefaction”. By Wiktionary contributors, CC BY-SA 4.0, via kaikki.org (dump of Oct 3 2026); text adapted and restructured. Language periods are conventional ranges, not dates for this word. License.

Etymograph / Middle French raréfaction / rarefaction

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