Definition from Wiktionary, the free dictionary
See also: blacklight
black + light "Black" being darker than "violet", so being beyond the violet end of the spectrum, hence ultraviolet; black also being a metaphor for non-visible, and ultraviolet being an invisible light
- Light bulb that emits ultraviolet light, usually used to create the illusion that anything white is glowing.
- (slang) ultraviolet radiation/light
light bulb that emits ultraviolet light