bulb

[buhlb]

SEE MORE SYNONYMS FOR bulb ON THESAURUS.COM

noun

Botany.

a usually subterranean and often globular bud having fleshy leaves emergent at the top and a stem reduced to a flat disk, rooting from the underside, as in the onion and lily.
a plant growing from such a bud.

any round, enlarged part, especially at the end of a cylindrical object: the bulb of a thermometer.

Electricity.

the glass housing, in which a partial vacuum has been established, that contains the filament of an incandescent electric lamp.
an incandescent or fluorescent electric lamp.

Anatomy. any of various small, bulb-shaped structures or protuberances: olfactory bulb; bulb of urethra.

medulla oblongata.

Building Trades. a rounded thickening at the toe of an angle iron or tee.

Nautical. a cylindrical or spherical prominence at the forefoot of certain vessels.

Photography. a shutter setting in which the shutter remains open as long as the shutter release is depressed. Symbol: B

Origin of bulb

1560–70; < Latin bulbus < Greek bolbós onion, bulbous plant

Related formsbulbed, adjectivebulb·less, adjective

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Related Words for bulb

corn, knob, head, ball, swelling, globe, tumor, protuberance, nub, tuber, bunch, nodule, corm

Examples from the Web for bulb

Contemporary Examples of bulb

So, at the Home Depot in Connecticut, a 40-watt bulb costs $4.97, and a 60-watt bulb costs $6.97.
Why You Should Give LED Light Bulbs for Christmas. Seriously.
Daniel Gross
December 4, 2013
In 25,000 hours a regular 75-watt bulb would use $262.50 of electricity.
Why You Should Give LED Light Bulbs for Christmas. Seriously.
Daniel Gross
December 4, 2013
The 40-watt bulb costs $9.97 and the 60-watt bulb retails for $12.97.
Why You Should Give LED Light Bulbs for Christmas. Seriously.
Daniel Gross
December 4, 2013
Specifically, the law said a bulb should provide 100 watts of brightness while using 72 watts or less.
The Best Green Idea in Obama’s Climate-Change Speech
Daniel Gross
June 25, 2013
By May, its bulb can grow as big as two centimeters, and turns pink and then a deep red as it matures.
The Wonderful World of Ramps
Jeff Gimmel
April 26, 2011

Historical Examples of bulb

I shall tell you the day when you are to put the bulb in the ground.
The Black Tulip
Alexandre Dumas (Pere)
Do you mean to say that the bulb has now been in the ground for six days?
The Black Tulip
Alexandre Dumas (Pere)
Amaryllis Formosissima was in bloom in one week after I planted the bulb.
The Mayflower, January, 1905
Various
And yet the bulb has not only an honourable character—it has a sort of sacred history.
Storyology
Benjamin Taylor
The stem is white, squamulose, bulb rugulose, ring superior and entire.
The Mushroom, Edible and Otherwise
M. E. Hard

British Dictionary definitions for bulb

bulb

noun

a rounded organ of vegetative reproduction in plants such as the tulip and onion: a flattened stem bearing a central shoot surrounded by fleshy nutritive inner leaves and thin brown outer leavesCompare corm

a plant, such as a hyacinth or daffodil, that grows from a bulb

See light bulb

a rounded part of an instrument such as a syringe or thermometer

anatomy a rounded expansion of a cylindrical organ or part, such as the medulla oblongata

Also called: bulbous bow a bulbous protuberance at the forefoot of a ship to reduce turbulence

Word Origin for bulb

C16: from Latin bulbus, from Greek bolbos onion

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for bulb

1560s, "an onion," from Middle French bulbe (15c.), from Latin bulbus "bulb, bulbous root, onion," from Greek bolbos "plant with round swelling on underground stem." Expanded by 1800 to "swelling in a glass tube" (thermometer bulb, light bulb, etc.).

bulb in Medicine

bulb

[bŭlb]

n.

A globular or fusiform anatomical structure or enlargement.

bulb in Science

bulb

[bŭlb]

A rounded underground storage organ that contains the shoot of a new plant. A bulb consists of a short stem surrounded by fleshy scales (modified leaves) that store nourishment for the new plant. Tulips, lilies, and onions grow from bulbs. Compare corm rhizome runner tuber.