bulb

Etymology

From Middle English bulb, bolbe, from Latin bulbus (“bulb, onion”), from Ancient Greek βολβός (bolbós, “plant with round swelling on underground stem”).

noun

1. (obsolete) An onion.
2. The bulb-shaped root portion of a plant such as a tulip, from which the rest of the plant may be regrown.
   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). 7 February 2015, Val Bourne, “The quiet man of the world of snowdrops”, in The Daily Telegraph (London), page G8
3. (dated, neuroanatomy) The medulla oblongata.
4. Any solid object rounded at one end and tapering on the other, possibly attached to a larger object at the tapered end.
   the bulb of the aorta
   1. A light bulb (not necessarily bulbous in shape).
      An incandescent bulb; an LED bulb; a fluorescent tube bulb
5. (nautical) A bulbous protuberance at the forefoot of certain vessels to reduce turbulence.

verb

1. (intransitive) To take the shape of a bulb; to swell.