light bulb

Alternative forms

• light-bulb, lightbulb

Etymology

light +‎ bulb

Noun

light bulb (plural light bulbs)

1. An evacuated glass bulb containing a metal filament which is heated by electrical resistance to produce light.
2. (by extension) An article that resembles such a bulb and converts electricity to light by any process.

   a fluorescent light bulb or an LED light bulb

3. (figuratively) Used in reference to the sudden arrival of a realization, an inspiration, an idea, or the like.
   • 1949, in Forbes (magazine), volume 64, page 18:

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

   • 2010, Sandy Abrams, Your Idea, Inc., Abrams Media, →ISBN, page xi:

     A light bulb went off in my head as I had an incredible idea for a beauty product.