trigonal

[trig-uh-nl] /ˈtrɪg ə nl/
adjective
1.
of, pertaining to, or shaped like a triangle; having three angles; triangular.
2.
Crystallography. having threefold symmetry.
Origin
1560-70; trigon + -al1
Related forms
trigonally, adverb
subtrigonal, adjective
British Dictionary definitions for trigonal

trigonal

/ˈtrɪɡənəl/
adjective
1.
another word for triangular (sense 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
trigonal in Science
trigonal
  (trī-gō'nəl)   
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.