Source : Webster's Revised Unabridged Dictionary (1913)

Dichroism \Di"chro*ism\, n. [Gr. ? two-colored; di- = di`s-
   twice + ? color.] (Opt.)
   The property of presenting different colors by transmitted
   light, when viewed in two different directions, the colors
   being unlike in the direction of unlike or unequal axes.

Source : WordNet®

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