photochromic

/ˌfoʊtoʊˈkroʊmɪk/
adjective
  1. Describing a material that changes color when exposed to light, especially ultraviolet light.
    • Many modern sunglasses use photochromic technology to adapt to changing light conditions.
    • The photochromic paint on the building's windows turns blue in bright sunlight.
    • Photochromic lenses darken automatically when you go outside on a sunny day.
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