trigonal

American  

[trig-uh-nl] / ˈtrɪg ə nl /

adjective

1. of, relating to, or shaped like a triangle; having three angles; triangular.

2. Crystallography. having threefold symmetry.

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trigonal British  

/ ˈtrɪɡənəl /

adjective

1. another word for triangular

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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trigonal Scientific  

/ trī-gō′nəl /

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.

2. Also called rhombohedral

3. See illustration at crystal

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Other Word Forms

• subtrigonal
  adjective
• trigonally
  adverb

Etymology

Origin of trigonal

First recorded in 1560–70; trigon + -al ¹

Example Sentences

In typical alkenes, the carbons adopt a trigonal planar geometry, creating a flat structure around the double bond.

From Science Daily • Jan. 23, 2026

They believed the reason trigonal chloride electrolytes can achieve low ionic conductivity is based on the variation of metal ion arrangements within the structure.

From Science Daily • Nov. 2, 2023

For example, an atom surrounded by three regions of electron density is sp2 hybridized, and the three sp2 orbitals are arranged in a trigonal planar fashion.

From Textbooks • Feb. 14, 2019

Therefore, the electron-pair geometry is trigonal planar, and the hybridization of the sulfur atom is sp2.

From Textbooks • Feb. 14, 2019

In the rhomobohedral or trigonal division of the hexagonal system there are seven symmetry-classes, all of which possess a single triad axis of symmetry.

From Encyclopaedia Britannica, 11th Edition, Volume 7, Slice 7 "Crocoite" to "Cuba" by Various

Related Words

• trilateral