operating theater

Inside a modern operating room An operating theater (or operation theater, OT; also known as an operating room or OR, as well as an operating suite or operation suite) is a facility within a hospital where surgical operations are carried out in an aseptic environment.

Historically, the term operating theater referred to a non-sterile, tiered theater or amphitheater in which students and other spectators could watch surgeons perform surgery. Contemporary operating rooms are usually devoid of a theater setting, making the term operating theater a misnomer in those cases.