cafetorium
A large room, usually in a school, used as both a cafeteria and an auditorium.
There is another combination which is regarded favorably, particularly where economy of space is a necessity. This is the combined cafeteria-auditorium unit and is often called a cafetorium or an auditeria.
Where it comes from
Blend of cafeteria + auditorium. First attested in the around 1950.
Adapted from the Wiktionary entry cafetorium (CC BY-SA 4.0).