Bulb

1. A modified bud consisting of a thickened globular underground stem serving as a reproductive structure. We planted many onion bulbs today.
2. Electric lamp consisting of a glass bulb containing a wire filament (usually tungsten) that emits light when heated. The light bulb burnt out this morning.
3. A rounded part of a cylindrical instrument (usually at one end). You must squeeze the bulb of the syringe to expel the fluid.