\ˈbəlb \

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 \ adjective

Examples of bulb in a Sentence

the bulb of the thermometer

Recent Examples on the Web

The ground floor is divided into viewing rooms with $1,000-a-bulb lighting, per the company, and ceiling rigs for moving heavy sculptures. Atossa Araxia Abrahamian, Longreads, "Tax-Free Storage Wars," 29 May 2018 The light-bulb moment for Kenta Maeda occurred June 9, long before the Dodgers right-hander transformed himself from starter to relief revelation during the team's World Series run. Mike Digiovanna, latimes.com, "Dodgers' Kenta Maeda is a starting pitcher with a reliever's mindset," 13 Apr. 2018 The lighting in the generally brilliantly bright Slidell Community Room was reduced to two single-bulb table lamps, shades removed. Carol Wolfram, NOLA.com, "Slidell tunes in for "An Evening with Ken Waldman"," 25 Feb. 2018 Keukenhof is probably the most popular tulip garden in the Netherlands, where 7 million tulip bulbs are planted each year, according to the office of tourism. Angela Fritz, Washington Post, "A sure sign that spring is here: Netherlands tulip farms are striped with color," 19 Apr. 2018 Over 9,000 bulbs were planted in preparation for the show. Chuck Crow, cleveland.com, "Annual Easter egg hunt at Cleveland Botanical Garden draws about 1,000 visitors," 31 Mar. 2018 Andrew Penketh Andrew Penketh Not all filament bulbs are created equal, though. Liz Stinson, Curbed, "Plumen makes a pair of not-so-tired Edison bulbs," 20 Mar. 2018 Tulip bulbs may be planted in the ground or in containers. Dan Gill, NOLA.com, "Will young radishes survive hard freezes?," 13 Jan. 2018 Due to this design, the Arc Light wall fixture's bulbs can be removed and rearranged while the thing's on. Rollin Bishop, Popular Mechanics, "This Righteous Lamp Wirelessly Lights Bulbs Like Magic," 3 Aug. 2015

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

3 Oct 2018

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 \

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 \

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

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