rareficationn.

1615 H. Crooke Μικροκοσμογραϕια 926 The Efficient cause of a bone is the Formatiue power which some call the Idoll or the Idea of him that ingendreth: this faculty vseth the heat for his architect, and the spirit for his chiefe worke-man, and to these the Philosopher attributeth Ordination, Secretion, Concretion, Densation and Rarification.

1686 R. Blome Gentlemans Recreation xix. 113/1 The heat of the Sun bringeth not so great a Rarification, or the cold so great a Condensation to the Air.

1729 S. Switzer Introd. Gen. Syst. Hydrostaticks & Hydraulicks I. i. 44 This Rarification, and consequently Expansion, must..take up so much Room for such a Change, that one should be very hard put to it to find where it is situated.

1794 R. J. Sulivan View of Nature I. 209 It carries the point of greater rarefication on the other side of the equator.

1847 Jrnl. Royal Geogr. Soc. 17 p. xl The desirableness of ascertaining..whether the W. wind which blows from the Atlantic a little to the N. of the Equator be due to the rarification of the air over the African continent.

1893 Times 3 Oct. 9/5 Rarefication in quality of two orders of impressions.

1938 Proc. Royal Soc. B. 125 132 The emphysematous lung is poor in blood, as the extreme rarefication of the lung tissue will lead to the closing and eventual obliteration of very large numbers of capillaries.

1985 A. C. Graham Reason & Spontaneity (BNC) 57 Ch'i is a universal fluid out of which bodies condense and into which they dissolve... Even the void is ch'i at the ultimate degree of rarefication.

2003 Ophthalmol. 110 87 Fig. 4 (caption) Complete fibrosis of the subepithelial tissue with rarification of blood vessels.