bulb

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noun \ˈbəlb\

: a rounded part of some plants that is under the ground and that grows into a new plant during the growing season

: a part that has a rounded shape

Full Definition of BULB

1

a :  a resting stage of a plant (as the lily, onion, hyacinth, or tulip) that is usually formed underground and consists of a short stem base bearing one or more buds enclosed in overlapping membranous or fleshy leaves

b :  a fleshy structure (as a tuber or corm) resembling a bulb in appearance

c :  a plant having or developing from a bulb

2

:  a bulb-shaped part; specifically :  a glass envelope enclosing the light source of an electric lamp or such an envelope together with the light source it encloses

3

:  a rounded or swollen anatomical structure

4

:  a camera setting that indicates that the shutter can be opened by pressing on the release and closed by ending the pressure

— bulbed \ˈbəlbd\ adjective

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Examples of BULB

1. the bulb of the thermometer

Illustration of BULB

Origin of BULB

Middle English, from Latin bulbus, from Greek bolbos bulbous plant

First Known Use: 15th century

bulb

noun \ˈbəlb\   (Medical Dictionary)

Medical Definition of BULB

1

:  a rounded dilation or expansion of something cylindrical <the bulb of a thermometer>; especially :  a rounded or pear-shaped enlargement on a small base <the bulb of an eyedropper>

2

:  a rounded part: as a :  a rounded enlargement of one end of a part—see bulb of the penis, bulb of the vestibule, end bulb, hair bulb, olfactory bulb b :  medulla oblongata; broadly :  the hindbrain exclusive of the cerebellum c :  a thick-walled muscular enlargement of the pharynx of certain nematode worms