Definition of "bulb"

bulb

/ˈbʌlb/

noun
plural bulbs
1. The bulb-shaped root portion of a plant such as a tulip, from which the rest of the plant may be regrown.
  Quotations
  the plants which grow in the earth from seed or bulbs.
  2005, Plato, translated by Lesley Brown, Sophist, page 265c
  Once it [a snowdrop variety] became established, some bulbs were lifted and passed on to be chipped (i.e. cut into small pieces and grown on).
  2015 February 7, Val Bourne, “The quiet man of the world of snowdrops”, in The Daily Telegraph (London), page G8
2. (dated, neuroanatomy) The medulla oblongata.
3. Any solid object rounded at one end and tapering on the other, possibly attached to a larger object at the tapered end.
  1. A light bulb (not necessarily bulbous in shape).
4. (nautical) A bulbous protuberance at the forefoot of certain vessels to reduce turbulence.
5. (obsolete) An onion.
verb
third-person singular simple present bulbs, present participle bulbing, simple past and past participle bulbed
1. (intransitive) To take the shape of a bulb; to swell.