Anesthesiology: The branch of medicine specializing in the use of drugs or other agents that cause insensibility to pain. Anesthesiology may also be defined as continuity of patient care involving preoperative evaluation, intraoperative and postoperative care and the management of systems and personnel that support these activities. The subspecialities within anesthesiology include cardiothoracic anesthesiology, critical care, neuroanesthesia, obstetrical anesthesiology, pain management, pediatric anesthesiology, and ambulatory anesthesia.

There is a major distinction between an anesthesiologist and an anesthetist. An anesthesiologist has a doctorate whereas an anesthetist does not. An anesthesiologist is a physician (or, less often, a dentist) who is specialized in the practice of anesthesiology while an anesthetist is a nurse or technician trained to administer anesthetics.