pleochroism
noun
ple·och·ro·ism plē-ˈä-krə-ˌwi-zəm 
: the property of a crystal of showing different colors when viewed by light polarized in different directions
pleochroic
ˌplē-ə-ˈkrō-ik
adjective 
Word History
Etymology
borrowed from German Pleochroismus, from pleo- pleo- + -chroismus, in Dichroismus dichroism
Note: The term was apparently introduced by the German mineralogist Wilhelm Haidinger (1795-1871); see "Ueber den Pleochroismus der Krystalle," Annalen der Physik und Chemie, Band 65, no. 5 (1845), pp. 1-29.
First Known Use
1854, in the meaning defined above
Medical Definition
pleochroism
noun
ple·och·ro·ism plē-ˈäk-rə-ˌwiz-əm
: the property of a crystal of showing different colors when viewed by light that vibrates parallel to different axes