A cloakroom, or sometimes coatroom, is a room for people to hang their cloaks.
From the en.wikipedia.org
Judges, politicians and assorted bigwigs rushed the coatroom and banged on the door.
From the washingtontimes.com
The next day, she came into work and went into the coatroom to change.
From the dailynews.com
A small TV set in the coatroom is tuned to Fox News.
From the washingtontimes.com
More examples
Cloakroom: a room where coats and other articles can be left temporarily
A cloakroom, or sometimes coatroom, is a room for people to hang their coats. They are typically found inside large buildings, such as gymnasiums, classrooms or meeting halls.