: 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
… a large underground rhizome, a bulblike growth that extends massive roots from its underside. —Elizabeth Schneider
Illustration of bulb
1 hyacinth
2 onion
3 tulip
4 lily
Examples of bulb in a Sentence
the bulb of the thermometer
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Gently squeeze the bulb and slowly fill your butt with water.—Alexander Cheves, Them., 16 May 2025 Watering them during this time can cause the bulbs to rot, especially in warm, humid conditions.—Leanne Potts, Better Homes & Gardens, 15 May 2025 The film opens on a flickering bulb on the ceiling of a highway rest stop, the camera taking us down to the building’s busy food court, though the family we’re meant to focus our attention on remain far away.—Josh Slater-Williams, IndieWire, 15 May 2025 Even a local florist may be hit with tariffs on getting bulbs from other countries.—Shelley E. Kohan, Forbes.com, 10 May 2025 See All Example Sentences for bulb
Word History
Etymology
Middle English, from Latin bulbus, from Greek bolbos bulbous plant
: 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
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