Sunglass

noun

1. A convex lens used to focus the sun's rays and produce heat, especially for ignition.
2. Eyeglasses with tinted or polarizing lenses to protect the eyes from the sun's glare.
3. A burning-glass.
4. Same as shade-glass; a screen of colored glass attached to a sextant to diminish the apparent brightness of the sun.
5. A convex lens of glass for producing heat by converging the sun's rays into a focus.