Bulb (?), n. [L. bulbus, Gr. : cf. F. bulbe.]
1. Bot.
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.
2. Anat.
A name given to some parts that resemble in shape certain bulbous roots; as, the bulb of the aorta.
Bulb of the eye, the eyeball. -- Bulb of a hair, the "root," or part whence the hair originates. -- Bulb of the spinal cord, the medulla oblongata, often called simply bulb. -- Bulb of a tooth, the vascular and nervous papilla contained in the cavity of the tooth.
3.
An expansion or protuberance on a stem or tube, as the bulb of a thermometer, which may be of any form, as spherical, cylindrical, curved, etc.
Tomlinson.
© Webster 1913.
Bulb, v. i.
To take the shape of a bulb; to swell.
© Webster 1913.