1. Electric lamp consisting of a transparent or translucent glass housing containing a wire filament (usually tungsten) that emits light when heated by electricity
   "He replaced the burnt-out light bulb in the lamp"; "They replaced the old incandescent lamps with more energy-efficient LED bulbs";
   - light bulb, lightbulb, incandescent lamp, electric light, electric-light bulb, light globe [Austral, NZ]
    
2. A modified bud consisting of a thickened globular underground stem serving as a reproductive structure
   "The tulip bulb lay dormant in the soil, waiting for spring"
    
3. Anything with a round shape resembling a teardrop
   "The light bulb illuminated the room"
    
4. A rounded part of a cylindrical instrument (usually at one end)
   "the bulb of a syringe"
    
5. A rounded dilation or expansion in a canal or vessel or organ
   "The olfactory bulb is involved in the sense of smell"
    
6. [archaic] Lower or hindmost part of the brain; continuous with spinal cord
   "The MRI showed abnormalities in the bulb";
   - medulla oblongata, medulla

Derived forms: bulbs

Type of: anatomical structure, bodily structure, body structure, complex body part, electric lamp, neural structure, part, portion, round shape, stalk, stem, structure

Part of: brain stem, brainstem, brain-stem, mercury thermometer, mercury-in-glass thermometer, syringe

Encyclopedia: Bulb