light bulb, lightbulb n. A glass bulb with metallic contacts on the outside connected to a wire filament (usually tungsten) inside that emits light when heated by passage of electricity through the filament; used as the replaceable light-emitting component of an electric lamp, flashlight, lighting fixture, etc.
Synonyms:light bulb, bulb, incandescent lamp, electric light, electric-light bulb.
... would you go about it," he shot at his audience, "if you were asked to measure the cubic contents of an electric light bulb?" ... — Radio Boys Loyalty - Bill Brown Listens In • Wayne Whipple