\ ˈbəlb How to pronounce bulb (audio) \
plural bulbs

Definition of bulb

1a : 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

Illustration of bulb

Illustration of bulb

bulb 1a: 1 hyacinth, 2 onion, 3 tulip, 4 lily

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Other Words from bulb

bulbed \ ˈbəlbd How to pronounce bulbed (audio) \ adjective
flasks with bulbed necks
bulblike \ ˈbəlb-​ˌlīk How to pronounce bulblike (audio) \ or bulb-like adjective
… a large underground rhizome, a bulblike growth that extends massive roots from its underside. — Elizabeth Schneider

Examples of bulb in a Sentence

the bulb of the thermometer

Recent Examples on the Web

Hanging bulbs top the dining room and galley-style kitchen, and walls of glass line the expansive living room. Jack Flemming, Los Angeles Times, "Josh Hutcherson’s Midcentury treehouse seeks $3.5 million in Hollywood Hills," 5 Aug. 2019 When the city began considering new streetlights, LED lights only came with bright white bulbs that gave off a cool-toned blue light. Katherine Rosenberg-douglas, chicagotribune.com, "West Nile virus could see an uptick in Chicago, a new study suggests. A culprit that’s saving the city millions could be to blame.," 30 July 2019 Edison bulbs are strung across the space where a garage housing a bar allows the outdoor area to function independently from the main restaurant, housed in a historic building sitting at the corner of Pearl and West Chestnut streets. Lindsey Mcclave, The Courier-Journal, "Too much cheese? How the pizza at this restaurant by the Big Four Bridge falls short," 24 July 2019 Soon, the marsupials that eat undesirable insects, snails and slugs were replaced with tree-climbing raccoons that dug up Coates’ flower bulbs and rinsed them in his birdbath before eating them. Janet Eastman, oregonlive.com, "What to do about cougars in the neighborhood, skunks under the house, bats in the attic," 19 July 2019 There are festivals to honor books, films, cranberries, winter holidays, theater, daffodils (more than three million blossoms, planted prolifically as the large deer population will not eat these unsavory bulbs). Danica Farley, Orange County Register, "A whale of a time in Nantucket," 17 July 2019 Smart bulbs also offer the perception of activity at home. Catharine Hamm, latimes.com, "High-tech and no-tech ways to keep your home safe without spending a fortune," 15 July 2019 Both Hoyt and Wiliams suggest buying bulbs that emit warm white light, rather than severe yellow or white light. Helen Carefoot, Twin Cities, "Don’t let a small balcony stop you from enjoying the space," 15 July 2019 Edison bulbs have new popularity today -- vintage design that adds a touch of class! Brenda Yenke, cleveland.com, "Clague House Museum & Milan’s Antiques Fest: Yenke Peddler antiques," 11 July 2019

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'bulb.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of bulb

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

History and Etymology for bulb

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

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Dictionary Entries near bulb






bulb angle


Statistics for bulb

Last Updated

8 Aug 2019

Look-up Popularity

Time Traveler for bulb

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

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More Definitions for bulb



English Language Learners Definition of bulb

: 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


\ ˈbəlb How to pronounce bulb (audio) \

Kids Definition of bulb

2 : a dormant stage of a plant that is formed underground and consists of a very short stem with one or more flower buds surrounded by special thick leaves
3 : a plant structure (as a tuber) that is somewhat like a bulb
4 : a rounded object or part the bulb of a thermometer


\ ˈbəlb How to pronounce bulb (audio) \

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

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More from Merriam-Webster on bulb

Spanish Central: Translation of bulb

Nglish: Translation of bulb for Spanish Speakers

Britannica English: Translation of bulb for Arabic Speakers

Britannica.com: Encyclopedia article about bulb

Comments on bulb

What made you want to look up bulb? Please tell us where you read or heard it (including the quote, if possible).


a period when something is suspended

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