Lightbulb
noun
An evacuated glass bulb containing a metal filament which is heated by electrical resistance to produce light.
(by extension) An article that resembles such a bulb and converts electricity to light by any process.
“a fluorescent light bulb”
Used in reference to the sudden arrival of a realization, an inspiration, an idea, or the like.
“a light bulb moment”
Synonyms: bulb, glow-lamp, incandescent lamp, light globe