'Pleochroism' definitions:

Definition of 'pleochroism'

From: WordNet
noun
The phenomenon of different colors appearing when certain crystals are viewed from different directions

Definition of 'Pleochroism'

From: GCIDE
  • Pleochroism \Ple*och"ro*ism\, n. [Gr.? mor? + ? color.] (Crystallog.) The property possessed by some crystals, of showing different colors when viewed in the direction of different axes. [1913 Webster]