Definition of pleochroic in English:



  • (of a crystal) absorbing different wavelengths of light differently depending on the direction of incidence of the rays or their plane of polarization, often resulting in the appearance of different colors according to the direction of view.

    • ‘The crystals lacked the characteristic pleochroic color scheme of piemontite.’
    • ‘It generally occurs as euhedral-subhedral hexagonal books, which commonly display a mottled green-brown pleochroic appearance.’
    • ‘In this book Joly also discussed the measurement of the radioactivity of rocks and the origin of pleochroic haloes.’
    • ‘Crystals are strongly pleochroic, resulting in distinctly different colors when viewed in different optic directions.’
    • ‘Augite is generally complexly zoned and pleochroic and has Ti-rich rims.’


Mid 19th century: from pleo- more + khrōs color + -ic.