indicator light
nounUK /ˈɪndɪkeɪtə laɪt/
US /ˈɪndɪkeɪtər laɪt/
A small light that shows you if something is on, off, or working.
The indicator light on the kettle turns green when the water is ready.
RELATED WORDS
OTHER MEANINGS
2. A light on a machine that warns you about a problem.
The indicator light flashed red when the engine got too hot.
3. A small light on a car's dashboard that shows a system is working.
An indicator light came on to remind the driver to fasten the seatbelt.
4. A light used to show which way a vehicle will turn.
He switched on the indicator light before turning left.