Noun
1. a modified bud consisting of a thickened globular underground stem serving as a reproductive structure
2. electric lamp consisting of a glass bulb containing a wire filament (usually tungsten) that emits light when heated
3. a rounded part of a cylindrical instrument (usually at one end);
"the bulb of a syringe"4. lower or hindmost part of the brain; continuous with spinal cord; (`bulb' is an old term for medulla oblongata);
"the medulla oblongata is the most vital part of the brain because it contains centers controlling breathing and heart functioning"5. a rounded dilation or expansion in a canal or vessel or organ