of, relating to, or shaped like a triangle; having three angles; triangular.
Crystallography. having threefold symmetry.
Origin of trigonal
Related formstrig·o·nal·ly, adverbsub·trig·o·nal, adjective
First recorded in 1560–70; trigon
Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
Related Words for trigonaltrilateral
Examples from the Web for trigonal
Historical Examples of trigonal
The leaves are trigonal; they are very short, and they are laid over each other like scales in four rows.
Trigonal trapezohedron (fig. 74), bounded by six trapezoidal faces.
All other forms, in which the faces are neither parallel nor perpendicular to the triad axis, are trigonal pyramids.
Fig. 73 represents a crystal of tourmaline with the trigonal prism , hexagonal prism , and a trigonal pyramid at each end.
Parietes ribbed, mottled purplish-red; orifice broad, trigonal, hardly toothed.
British Dictionary definitions for trigonal
Also: rhombohedral relating or belonging to the crystal system characterized by three equal axes that are equally inclined and not perpendicular to each other
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
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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.
The American Heritage® Science Dictionary
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