bulb Definition

bulb
noun

1. In certain plants, eg tulip and onion: a swollen underground organ that functions as a food store and consists of a modified shoot, with overlapping layers of fleshy leaf bases or scales, and roots growing from its lower surface.
2. A flower grown from a bulb, eg a daffodil and hyacinth.
3. A light-bulb.
4. Anything which is shaped like a pear or a bulb (sense 1).

Etymology: 16c in obsolete sense ‘onion': from Greek bolbos onion.