light bulb

noun

Etymology: From light + bulb First attested in 1885.

1. An evacuated glass bulb containing a metal filament which is heated by electrical resistance to produce light.

   “Atticus did something that interested us: he came into the livingroom carrying a long electrical extension cord. There was a light bulb on the end.”

2. An article that resembles such a bulb and converts electricity to light by any process.

   “a fluorescent light bulb”

   “an LED light bulb”

3. Used in reference to the sudden arrival of a realization, an inspiration, an idea, or the like.

   “a light-bulb moment”

   “Figuratively speaking, a light-bulb flashed over Galvin's head early this year, and in March–along […]”