light bulb noun
plural light bulbs
plural light bulbs
Learner's definition of LIGHT BULB
[count]
: a glass bulb or tube that produces light when it is supplied with electricity电灯泡；电灯管 — called also bulb
a light bulb goes off/on
chiefly US, informal
◊ When a light bulb goes off/on (in your head), you suddenly understand something or have a great idea.突然明白；恍然大悟；灵光一现。