An operating theater (also known as an operating room, operating suite, operation theatre or operation suite) is a facility within a hospital where surgical operations are carried out in a sterile environment.
Historically, the term “operating theatre” referred to a non-sterile, tiered theater or amphitheater in which students and other spectators could watch surgeons perform surgery. Contemporary operating rooms are devoid of a theater setting (though some in teaching hospitals may have small galleries), making the term “operating theater” a misnomer for the modern facility.