Vomitorium - Then: Privately, it was a special room, adjoining the dining hall, where gluttonous eaters who had swilled too much rich and exotic food might throw up the contents of their stomach in order to return to their couches empty enough to enjoy the pleasures of still more food. A simple rock rectangle over which diners leaned against a chest high wooden beam. The pressure of the beam did all the work, not by sticking a finger, or anything else down your throat. At the end of the night, a slave would collect the slop for the tanners; gastric acids were excellent for treating leather.
Now: When in describing a Roman coliseum, It is essentially the exit which allows the stadium to disgorge (or vomit) its spectators in a short time.