rarefactionn.
/ˌrɛːrᵻˈfakʃn/, U.S. /ˌrɛrəˈfækʃ(ə)n/ 1.
a. The state of being rarefied; the process of becoming rarefied; reduction in the density of something. Now chiefly with reference to the air or other gas.
ΘΚΠ
the world > matter > constitution of matter > lack of density > [noun] > reduction in density > rarefaction
subtiliationa1398
subtlinga1398
rarefaction1572
subtilization1603
rarefication1615
subtilizing1618
extenuation1655
1572 J. Jones Bathes of Bathes Ayde ii. f. 11 Bycause great rarefaction standeth with great heate.
1576 H. Gilbert Disc. Discov. New Passage Cataia sig. Ciiiiv The Tides, and courses of the Sea, are maintained by their interchangeable motions: as freash riuers are by springes, by ebbing and flowing, by rarifaction and condensation.
1603 P. Holland tr. Plutarch Morals 1318 To clense and purifie the aire by this rarefaction and subtilization.
1626 F. Bacon Sylua Syluarum §30 In Gunpowder, the Force of it hath been ascribed to Rarefaction of the Earthy Substance into Flame.
1707 J. Floyer Physician's Pulse-watch 69 In those Persons who have the best Tempers, the Blood and Spirits have a moderate Rarifaction.
1716 J. Perry State of Russia 116 By Reason of the Rarefaction and Subtileness of the Air..it incessantly freezes.
1785 Mem. Amer. Acad. Arts & Sci. 1 498 The spring of the air under the valve is much weakened by rarefaction.
1807 T. Young Course Lect. Nat. Philos. I. xxiv. 297 The mercury was depressed more than two inches, in consequence of the rarefaction which the current produced in the air of the box.
1863 J. Tyndall Heat x. 281 The condensation and rarefaction constitute what is called a sonorous pulse or wave.
1937 A. J. Cronin Citadel iv. xii. 353 By introducing a small bromoform manometer close to the needle we avoid rarefaction.
1949 R.-M. S. Heffner Gen. Phonetics iii. 43 The compressed air expands back into the region of rarefaction from which it was driven.
2001 C. H. Lineweaver in P. Coles Routledge Compan. New Cosmol. i. v. 88 Compression and rarefaction of this ‘baryon-photon’ fluid creates hot and cold spots.
b. As a count noun: an instance of this; a region where the air is rarefied.
ΘΚΠ
the world > matter > constitution of matter > lack of density > [noun] > reduction in density > rarefaction > instance of
rarefaction1664
1664 Duchess of Newcastle Philos. Lett. iii. 269 And not onely a difference in the aforesaid qualities of heat, cold, moisture, and drought, but also in all other motions, as Dilations, Contractions, Rarefactions, Densations, &c. nay, in their Mixtures and Temperaments.
1700 S. Parker 6 Philos. Ess. i. 11 I much question whether you could find a motion so brisk among the parts of that Liquid, as to cause rarefactions.
1773 J. Mills Ess. Weather (ed. 2) 47 There are divers causes which make these alterations in the equipoise of the atmosphere; such as rarefactions or condensations in one part more than in another.
1834 M. Somerville On Connexion Physical Sci. (1849) xvi. 144 A regular series of condensations and rarefactions.
1873 W. Lees Acoustics i. i. 10 An undulation or wave..consists of two parts—a condensation and a rarefaction.
1966 L. S. V. Judson & A. T. Weaver Voice Sci. iii. 94 A rarefaction traveling down the tube is maintained because the walls of the tube prevent the outside air from coming in.
1998 Automotive Engineer June 16/2 The front and rear of the diaphragm radiate sound in anti-phase: as a compression is being generated on one side, a rarefaction is created on the outer.
c. In extended use: expansion; refinement, purification.
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1673 A. Marvell Rehearsall Transpros'd: Second Pt. 249 Least they [sc. laws]..lose in strength what they gain by extension and rarefaction.
1789 ‘A. Pasquin’ Poems II. 32 She oft fills in thought a vast compass of action, When her fame's but expanded by false rarefaction.
1818 S. T. Coleridge Coll. Lett. (1959) IV. 830 The anxious self-doubting & inward perplexity which accompanied it's gradual rarefaction and final evanescence, has never ceased to give an interest to the name of Godwin.
1873 J. A. Symonds Stud. Greek Poets vi. 171 Arriving at monotheism by a process of rarefaction and purification.
1912 Times 29 June 6/2 Political science suffers from the same defect as political economy in the earlier part of the nineteenth century. There is a certain rarefaction in the atmosphere.
1963 Italica 40 129 The passage from cosmic and mental grossness to Paradisal rarefaction, which involves purity and intensity of being.
1999 Independent (Nexis) 9 May 12 The grace, the airy rarefaction, of his paintings.
2. Medicine. Diminution of the density of a tissue, organ, etc., esp. by loss of cells; loss of density in a radiological image, esp. of a bone; loss of blood vessels from a vascular tree.
ΘΚΠ
the world > health and disease > ill health > a disease > diseases of tissue > disorders of bones > [noun] > decay or erosion
caries1634
cariosity1638
spina ventosa1684
cariousness1818
osteoporosis1841
rarefaction1850
osteolysis1875
osteitis fibrosa1910
porosis1926
osteodystrophia fibrosa1928
osteodystrophy1930
1850 C. H. Moore tr. C. von Rokitansky Man. Pathol. Anat. III. ix. 171 Expansion, or rarefaction [Ger. Rarefaction], though often combined with softening of bone, must yet be distinguished from it. The former is produced by dilatation of the Haversian canals and cells, and constitutes the disease which is named osteoporosis.
1873 Lancet 18 Jan. 88/1 Loosening or rarefaction of tissue in the neighbourhood of ulcers.
1898 T. C. Allbutt et al. Syst. Med. V. 605 In others there is..thickening or rarefaction of skull bones.
1954 Amer. Jrnl. Roentgenol. Rad. Ther. & Nucl. Med. 72 591/1 At nine seconds the areas of rarefaction within the opacification of the liver begin to be much more apparent.
1967 Brain 90 38 There was moderate rarefaction of the anterior roots in the cervical region only.
1977 Radiology 125 425 Common radiographic characteristics include an intradiploic rarefaction, a well-defined margin with or without sclerosis, [etc.].
1997 Jrnl. Clin. Investig. 99 1873 The dermal vessels of men who express a familial predisposition to high BP exhibit increased minimum resistance and capillary rarefaction.
3. Ecology. A statistical technique for comparing biotic diversity between samples of different sizes on the basis of estimating the expected diversity of a small sample from that of a larger one.
ΚΠ
1968 H. L. Sanders in Amer. Naturalist 102 279 In this paper a methodology is presented for measuring diversity based on rarefaction of actual samples.
1991 R. S. K. Barnes & K. H. Mann Fund. Aquatic Ecol. (ed. 2) iv. 80/1 Sanders (1968) used the rarefaction method to show that the number of species increases rapidly with sample size for groups of fauna such as polychaetes and molluscs, in continental slope and abyssal plain ocean transects, and in tropical shallow waters.
2001 Evolution 55 1566/2 We have two lines of evidence supporting our hypothesis that mortality driven rarifaction contributes to the loss of spatial genetic structure by the juvenile stage.
2002 P. Herring Biol. Deep Ocean xi. 242 These relationships are expressed graphically as ‘rarefaction’ curves, which describe empirically how the number of species present in the samples scales with the number of individuals collected.
This entry has been updated (OED Third Edition, December 2008; most recently modified version published online March 2022).
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