At the base of the hair root is a small ball-like formation called a bulb.

VOA: special.2011.04.05

Certainly if you buy them out somewhere you're going to get one that's maybe the size of a light bulb, but it's like the flood light in your backyard or something, it's a huge light.

当然,你在外购买时,倒是有可能买到灯泡大小的,不过是你家后院强光灯大小的灯泡,巨大的灯泡

耶鲁公开课 - 关于食物的心理学、生物学和政治学课程节选