Noun

1. A modified bud consisting of a thickened globular underground stem serving as a reproductive structure
2. Electric lamp consisting of a transparent or translucent glass housing containing a wire filament (usually tungsten) that emits light when heated by electricity
3. A rounded part of a cylindrical instrument (usually at one end)
4. Anything with a round shape resembling a teardrop
5. Lower or hindmost part of the brain; continuous with spinal cord; (`bulb' is an old term for medulla oblongata)
6. A rounded dilation or expansion in a canal or vessel or organ