merohedrismn.
/ˌmɛrə(ʊ)ˈhiːdrɪz(ə)m/, U.S. /ˌmɛroʊˈhidrɪz(ə)m/ Crystallography.
The state or property of being merohedral.
ΚΠ
1878 Nature 26 Dec. 171/1 In his discussion of merohedrism the author has not attended to the limiting condition..that the merohedral form should not be identical with the characteristic form of a system of lower symmetry.
1888 J. J. H. Teall Brit. Petrogr. 438 Merohedrism, a crystallographic term embracing both hemihedrism and tetartohedrism.
1899 W. J. Lewis Crystallogr. 259 The views underlying the ideas of merohedrism lead to inconsistencies.
1938 Amer. Mineralogist 23 178 (heading) Merosymmetry versus merohedrism.
1987 R. L. Bates & J. A. Jackson Gloss. Geol. (ed. 3) 412/2 Merohedral, said of crystal classes in a system, the general form of which has only one half, one fourth, or one eighth the number of equivalent faces of the corresponding form in the holohedral class of the same system. This condition is known as merohedrism.
This entry has been updated (OED Third Edition, September 2001; most recently modified version published online March 2022).
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