bulb

1. N-COUNT A bulb is the glass part of an electric light or lamp, which gives out light when electricity passes through it. 电灯泡

The stairwell was lit by a single bulb. 楼梯间只有一盏灯照明。

2. N-COUNT A bulb is a root shaped like an onion that grows into a flower or plant. 球茎

...tulip bulbs. …郁金香球茎。