plural bulbs
1
a
: a resting stage of a plant (such 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 (such 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 adjective
flasks with bulbed necks
bulblike adjective
or bulb-like
… a large underground rhizome, a bulblike growth that extends massive roots from its underside. Elizabeth Schneider

Illustration of bulb

Illustration of bulb
  • 1 hyacinth
  • 2 onion
  • 3 tulip
  • 4 lily

Examples of bulb in a Sentence

the bulb of the thermometer
Recent Examples on the Web To keep from being poisoned by any of these plants, keep seeds, bulbs and small fruits away from small children and teach them not to put plants into their mouths. Sara Okeefe, The Mercury News, 16 Mar. 2024 The same is true of the physical production, which glistens in the reflection of a downstage water’s edge, below a canopy of A-frames and vertical fluorescent bulbs glowing like stationary falling stars (the set is by David Zinn and Brett J. Banakis, the lighting by Ben Stanton). Naveen Kumar, Washington Post, 15 Mar. 2024 King launched online courses as well as an e-commerce service for shipping flowers that could survive the trip, like bulbs and peonies. Max Zahn, ABC News, 15 Mar. 2024 Amaryllis bulbs can survive in the ground in Zones 8 and warmer to naturally bloom in spring. Marissa Wu, Southern Living, 12 Mar. 2024 The man was changing the electric bulbs on the clock on the east side of the Paramount Building. Megan Ditrolio, New York Times, 29 Feb. 2024 During the 1600s in Holland, tulips were so valuable that their bulbs were worth more than gold. Deb Wiley, Better Homes & Gardens, 19 Feb. 2024 The underground bulb soon produced offshoots, called bulblets, eventually filling the pot. Kenneth Setzer, Miami Herald, 30 Jan. 2024 The book is about flower bulb grower Luther Gage, who cultivated the giant Tecolote ranunculus, which can be seen at The Flower Fields in Carlsbad. Linda McIntosh, San Diego Union-Tribune, 2 Mar. 2024

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'bulb.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

Etymology

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

First Known Use

15th century, in the meaning defined at sense 1a

Time Traveler
The first known use of bulb was in the 15th century

Dictionary Entries Near bulb

Cite this Entry

“Bulb.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/bulb. Accessed 29 Mar. 2024.

Kids Definition

bulb

noun
1
a
: an underground resting stage of a plant (as an onion or tulip) consisting of a short stem base bearing one or more buds enclosed in overlapping leaves
b
: a fleshy structure (as a tuber or corm) resembling a bulb in appearance or function
2
: a rounded object or part shaped more or less like a bulb
a flashlight bulb

Medical Definition

bulb

noun
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

More from Merriam-Webster on bulb

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