This is the 9836th most frequent Russian word.
аварийного
"Emergency" or "of an accident."
Here, 'аварийного' is used as an adjective describing the type of exit, specifically one intended for emergencies.
На стене висел знак аварийного выхода.
On the wall, there was a sign for the emergency exit.
In this sentence, 'аварийного' describes the lighting, indicating that it is used under emergency conditions.
Я включил аварийного освещение в доме.
I turned on the emergency lighting in the house.
The word 'аварийного' refers to equipment that is designed for use during emergencies or has malfunctioned.