bulb

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. 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.
2. n. Botany A similar underground stem or root, such as a corm, rhizome, or tuber.
3. n. Botany A plant that grows from a bulb.
4. n. A rounded projection or part: the bulb of a syringe.
5. n. An incandescent lamp or its glass housing.
6. n. Anatomy A rounded dilation or expansion of a canal, vessel, or organ.

Century Dictionary and Cyclopedia

1. n. A form of leaf-bud, usually subterranean, in which the stem is reduced to a flat disk, rooting from the under side, and bearing above closely appressed fleshy leaves. In the tunicated or coated bulb these leaves are in the form of broad, closely concentric coatings, as in the hyacinth and onion; in the scaly bulb they are narrow, thick, and imbricated, as in the lily. The so-called solid bulb, as in the crocus and gladiolus, is more properly a corm, or short thick root-stock, inclosed within the dried sheathing bases of a few leaves.
2. n. Any protuberance or expansion resembling a bulb, especially an expansion at the end of a stalk or long and slender body: as, the bulb of a thermometer; the bulb of the aorta.
3. n. plural The tonsils.
4. To project or be protuberant.

Wiktionary

1. n. Any solid object rounded at one end and tapering on the other, possibly attached to a larger object at the tapered end.
2. n. A light bulb.
3. n. The bulb-shaped root portion of a plant such as a tulip, from which the rest of the plant may be regrown.
4. n. nautical a bulbous protuberance at the forefoot of certain vessels to reduce turbulence.
5. v. intransitive To take the shape of a bulb; to swell.

GNU Webster's 1913

1. n. (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. n. (Anat.) A name given to some parts that resemble in shape certain bulbous roots.
3. n. 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.
4. n. a light bulb.
5. v. To take the shape of a bulb; to swell.

WordNet 3.0

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