backuplight
nounUK /ˈbækʌplaɪt/
US /ˈbækʌplaɪt/
A backuplight is a light that turns on when the main light stops working.
When the power went out, the backuplight above the door helped us see.
RELATED WORDS
OTHER MEANINGS
2. A light on a machine that shows it is running on its backup power.
The backuplight blinked red while the computer used its battery.
3. A second light used behind something to make it easier to see.
The photographer put a backuplight behind the model to make her stand out.
4. A small light kept in a car or bag for emergencies.
He kept a backuplight in the trunk in case of a flat tire at night.