Wiktionary
n. A device in a public building that displays where the exit is.
Wikipedia
An exit sign is a device in a public facility (such as a building, aircraft or boat) denoting the location of the closest emergency exit in case of fire or other emergency.
Most relevant codes ( fire, building, health or safety) require exit signs to be permanently lit.
Exit signs are designed to be absolutely unmistakable and understandable to anyone. In the past this generally meant exit signs that show the word "EXIT" or the equivalent in the local language, but increasingly exit signs around the world are in pictogram form, with or without text supplement.
Usage examples of "exit sign".
An Exit sign hung from the ceiling, the arrow pointing to the right.
The other took the hint, easing Lobot toward the nearest exit sign.
And there on the stage in front of them, above them, was the red glow of the exit sign.
Marie slipped out of the linen closet, a stack of towels over her shoulder, and ran to the bisecting corridor and the Exit sign.
He spun around only to watch helplessly as the heavy, muscular nurse ran out of his room and down the hall to a door beneath a red-lettered Exit sign.
Then, unable to see an exit sign for a staircase, he turned quickly to check the other end, the north end of the hallway.
The bullets struck a lighted Exit sign on the ceiling, shattering the bulb and darkening the hall even more—.
Immediately I looked across the way, but he did not exit beneath the exit sign.