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1. A substance that occurs in three distinct crystalline forms.
2. One of the crystalline forms in which a trimorphic substance occurs.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.


1. (Geological Science) a substance, esp a mineral, that exists in three distinct forms
2. (Geological Science) any of the forms in which such a structure exists
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014


(ˈtraɪ mɔrf)

a substance existing in three structurally distinct forms; a trimorphous substance.
[1905–10; < Greek trímorphos having three forms. See tri-, -morph]
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.
References in periodicals archive ?
Groutite, an orthorhombic trimorph of (monoclinic) manganite and feitknechtite, is a rare species known in good specimens chiefly from the Iron Range of Minnesota (in 1980 some superb specimens were collected in the Roberts mine, Cayuna Range, Crow Wing County).
The yellow patina (already mentioned) is lepidocrocite, chemically identical with goethite, its trimorph. As measured by SEM imaging, the patina consists of a uniform, 1.6-[mu]m-thick layer of lepidocrocite (very unlikely to have been applied artificially) upon calcite (Fig.
Brookite, the orthorhombic trimorph of [TiO.sub.2], occurs in fine, doubly terminated, deep reddish brown crystals in chert cutting Hale Creek, Trinity County, California.