bulb /bʌlb/ BrE AmE noun [countable]
[ Date: 1500-1600 ; Language: Latin ; Origin: bulbus , from Greek bolbos 'plant with a bulb' ]
1 . the glass part of an electric light, that the light shines from SYN light bulb :
a 100-watt bulb
2 . a root shaped like a ball that grows into a flower or plant:
tulip bulbs