bulb

(noun) a modified bud consisting of a thickened globular underground stem serving as a reproductive structure.

(noun) electric lamp consisting of a transparent or translucent glass housing containing a wire filament (usually tungsten) that emits light when heated by electricity. Synonyms: light bulb, lightbulb, incandescent lamp, electric light, electric-light bulb.

(noun) a rounded part of a cylindrical instrument (usually at one end). Example: "The bulb of a syringe."

(noun) anything with a round shape resembling a teardrop.

(noun) lower or hindmost part of the brain; continuous with spinal cord; (`bulb' is an old term for medulla oblongata). Synonyms: medulla oblongata, medulla. Example: "The medulla oblongata is the most vital part of the brain because it contains centers controlling breathing and heart functioning."

(noun) a rounded dilation or expansion in a canal or vessel or organ.