photochromism

• a word derived from photochromic.
  photochromic

  adjective

  (of chemically treated glass or plastic) capable of darkening or changing color when exposed to light.

More Suggestions

• photochromy
• phototropism
• photoperiodism
• thermochromism
• phytochrome
• monochromatism
• photochemistry
• ferrochromium
• hypochromia