Source : Webster's Revised Unabridged Dictionary (1913)

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.

Source : WordNet®

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