bulb

noun

1. an underground bud that sends down roots and consists of a very short stem covered with leafy scales or layers, as in a lily, onion or hyacinth
2. a corm, tuber, or tuberous root resembling a bulb, as in a crocus, dahlia or cyclamen
3. any plant that grows from a bulb
4. anything shaped like a bulb; rounded thing or enlarged part: an electric light bulb, the bulb of a syringe
5. Anat.
   1. an enlargement on some tissues, organs, or tubes, as at the root of a hair
   2. Obsolete medulla oblongata