A spheroidal body growing from a plant either above or below the ground (usually below), which is strictly a bud, consisting of a cluster of partially developed leaves, and producing, as it grows, a stem above, and roots below, as in the onion, tulip, etc. It differs from a corm in not being solid.
- Botany A short, modified, underground stem surrounded by usually fleshy modified leaves that contain stored food for the shoot within: an onion bulb; a tulip bulb.
- Botany A similar underground stem or root, such as a corm, rhizome, or tuber.
- Botany A plant that grows from a bulb.
- A rounded projection or part: the bulb of a syringe.
- An incandescent lamp or its glass housing.
- Anatomy A rounded dilation or expansion of a canal, vessel, or organ.