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See more synonyms for trigonal on Thesaurus.com
  1. of, relating to, or shaped like a triangle; having three angles; triangular.
  2. Crystallography. having threefold symmetry.
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Origin of trigonal

First recorded in 1560–70; trigon + -al1
Related formstrig·o·nal·ly, adverbsub·trig·o·nal, adjective
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

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British Dictionary definitions for trigonal


  1. another word for triangular (def. 1)
  2. Also: rhombohedral relating or belonging to the crystal system characterized by three equal axes that are equally inclined and not perpendicular to each other
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Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

trigonal in Science


  1. Relating to a crystal having three axes of equal length intersecting at oblique angles. This crystal system is considered a subset of the hexagonal system. The mineral quartz has trigonal crystals. Also called rhombohedral See illustration at crystal.
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The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.