Longman Dictionary of Contemporary English
operating room
noun
EXAMPLES FROM CORPUS
▪ For exam-ple, an emergency or operating room is not the best environment for monitoring subtle variations in heartbeats.
▪ George asked the patient if he remembered the moment in the operating room when he heard that music.
▪ George Cowley arrived at the hospital just as Doyle's now unconscious body was being wheeled into the emergency operating room.
▪ In the operating room you can only see my eyes.
▪ Mary had prepared an operating room.
▪ The reek poured unabated out of the operating room.
▪ When he came to the centre I was already inside the operating room.
Wiktionary
operating room
n. A room in a hospital used for performing surgery.
WordNet
operating room
n. a room in a hospital equipped for the performance of surgical operations; "great care is taken to keep the operating rooms aseptic" [syn: OR, operating theater, operating theatre, surgery]