General English

General Science

  • noun a glass ball that produces light when electricity is supplied


  • noun an underground plant organ of fleshy scale leaves and buds. It can be planted and will produce flowers and seed.


  • noun a glass ball inside a lamp that gives electric light
  • noun something shaped like a lamp bulb

Cars & Driving

  • noun a gas-filled, glass envelope (often pear-shaped if not actually pear-sized) containing a thin metal filament which lights up when an electric current is passed through it


  • A glass housing which encloses the elements of electric lamps, electron tubes, and similar devices. A bulb may or may not be evacuated. Also called envelope (1).


  • noun a round part at the end of an organ or bone

Origin & History of “bulb”

Bulb can be traced back to Greek bólbos, which was a name for various plants with a rounded swelling underground stem. In its passage via Latin bulbus to English it was often applied specifically to the ‘onion’, and that was its original meaning in English. Its application to the light bulb, dating from the 1850s, is an extension of an earlier 19th-century sense ‘bulb-shaped swelling in a glass tube’, used from the 1830s for thermometer bulbs.