It is. But doesn’t fit with the rest of the sentence. “In a television studio, theatre or concert hall, the room where performers await their entrance.” https:

It is. But doesn’t fit with the rest of the sentence. “In a television studio, theatre or concert hall, the room where performers await their entrance.” https://en.wiktionary.org/wiki/green_room https://en.wiktionary.org/wiki/green_room