Having three angles, or corners; triangular; as, a trigonal stem, one having tree prominent longitudinal angles.
a. (Gr. trigonos, triangular) triangular in cross-section as applied to stems.
having three-fold symmetry
Three- angled, triangular in cross section. See also: trigonous.
(trig´-o-nal) A crystal system of threefold symmetry that is often considered as part of the hexagonal system since the lattice may be either hexagonal or rhombohedral.