1. Capable of changing color or becoming darker when exposed to light, especially ultraviolet light, and returning to the original color when the light source is removed.
Usage: Commonly used in the context of eyeglasses and optical materials.

Examples

• Photochromic lenses automatically darken in sunlight to protect your eyes.
• She bought photochromic glasses that adjust to different lighting conditions.
• The photochromic coating on the windshield helps reduce glare while driving.
• These photochromic materials are used in smart windows for energy efficiency.
• The photochromic reaction happens within seconds of exposure to UV light.