| 释义 |
bulb
I. \ˈbəlb, ˈbəu̇b\ noun
(-s)
Etymology: Latin bulbus onion, bulb, from Greek bolbos bulbous plant; akin to Armenian bolk radish and perhaps to Sanskrit balbaja yard grass (Eleusine indica)
1. : a mass of overlapping membranous or fleshy leaves on a short stem base enclosing one or more buds that may develop under suitable conditions into new plants and constituting the resting stage of many plants (as lily, onion, hyacinth, tulip) — distinguished from corm, rhizome, tuber
2.
a. : a fleshy tuber, corm, or other plant structure resembling a bulb in appearance
< a dahlia bulb >
< a crocus bulb >
— not used technically
b. Britain : a fleshy bulbous root
< beet and turnip bulbs >
3. : a plant having or developing from a bulb
< spring-flowering bulbs >
4. : a protuberance resembling a plant bulb: as
a. : a rounded dilatation 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 >
b. : the thickened edge characteristic of certain construction elements (as a bulb angle or bulb bar)
c. : a rounded or pear-shaped glass envelope enclosing the light source of an incandescent or other electric lamp; broadly : such an envelope together with the light source it encloses
< a fluorescent bulb >
— see incandescent lamp illustration
5. : a rounded part: as
a. : a rounded enlargement of one end of a part
< the bulb of the urethra >
— see end bulb, olfactory bulb
b. : medulla oblongata; broadly : the rhombencephalon exclusive of the cerebellum
c. : the upper portion of the heel of a horse's hoof
d. : a thick-walled muscular enlargement of the pharynx of certain nematode worms
e. : the modified tarsal tip of a male spider that contains the coiled seminal receptacle, is often highly complex, and constitutes a character of taxonomic importance
6. [so called from the pneumatic bulb sometimes used to control the shutter] : a camera setting that indicates that the shutter can be opened by pressing on the release and closed by ending the pressure and that is used in making short time exposures and flashlight exposures — abbr. B.
 [bulb 1a: 1 hyacinth, 2 onion, 3 tulip, 4 lily]
II. intransitive verb
(-ed/-ing/-s)
1. : to assume a bulbous form : swell
2. of a plant : to produce bulbs
< the onions bulbed poorly in this cold wet season > |