In a Nutshell
It’s commonly taught that Ancient Romans had special rooms called Vomitoriums and that said rooms were used for the express purpose of vomiting after a large meal. In actuality, though vomitoriums did exist, they were merely very large corridors commonly found in theaters and public venues, that could facilitate a large number of people passing through them. The word vomitorium was used to describe the spewing out of people rather than their lunch.
The misconception is thought to stem from early historians being unable to read Latin inscriptions and taking the term “vomitorium”, literally.
The Whole Bushel
The vomitorium is a favorite topic very lazy history teachers. According to some, it was a room in which the Roman elite would forcibly empty their stomachs to make room for more food.
However, such a room has never been or observed or noted in any literature involving the ancient Roman populace. However, the vomitorium did exist and it was used by many, many Roman’s, though not for the purpose you’re thinking of.
The term vomitorium comes from earlier Latin word “vomere” which literally means “to spew forth”. Though this term could arguably refer to the act of voiding ones bowels, it was used in Roman times to refer to the large entrance/exit corridors found in amphitheaters.
The confusion is thought to have stemmed from early historians not being able to read Latin and thus presuming that a vomitorium was a room used for the act of, well, vomiting.
Today we know better. Mostly.
Show Me The Proof
The Ancient Standard: Veni, Vidi… Vomit? (1st C BC)
Google Books: The Story of the Roman Amphitheatre
Oxford Dictionary: Vomitorium