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
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
The bulbs are shatterproof, solar-powered and easy to use. Nora Colomer, FOXNews.com, 31 Mar. 2025 In Eau Claire, Wisconsin, some city streetlights took on a blueish-purple tint the same year, as did bulbs in the village of Schaumburg, Illinois and Palm Beach, Florida. Elizabeth Weise, USA Today, 29 Mar. 2025 For most Southern gardeners, April brings a floral showcase of bulbs, perennials, shrubs, and trees. Mary Marlowe Leverette, Southern Living, 27 Mar. 2025 Theirs sits on the ground, just bare bulbs screwed into the ends of copper piping strung with wires, powering through a wondrous cycle of dimming and illumination, conjuring electricity’s arrival to the Marble Palace long ago. Lori Waxman, Chicago Tribune, 24 Mar. 2025 See All Example Sentences for bulb

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

Browse Nearby Words

Cite this Entry

“Bulb.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/bulb. Accessed 4 Apr. 2025.

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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