What is "trichroism"

Trichroism \Tri"chro*ism\, n. [Pref. tri- + Gr. ? color: cf. F. trichro["i]sme.] (Min.) The quality possessed by some crystals of presenting different colors in three different directions.

n. The property of some optically anisotropic crystals of transmitting different colours of light in three different spatial directions.

n. pleochroism of a crystal so that it exhibits three different colors when viewed from three different directions