lightbulb
n. countablen. a glass container that produces light when electricity passes through it. You find them in every room of a house to help you see at night.
n. a glass container containing a filament or gas that produces light when an electric current is passed through it. Often used metonymically to refer to the concept of an idea or the person who had it.
The lightbulb in the kitchen is broken.
He replaced the old lightbulb with a more energy-efficient LED version to save on his electricity bill.
While the lightbulb is often credited to Edison, the history of electric lighting is a complex web of patents and incremental improvements by numerous inventors across several decades.
Calque from Cantonese 電燈泡／电灯泡 (din6 dang1 paau1), as though the third person is a light bulb in the background.