A branch of medicine specializing in the use of drugs, or other agents, that cause insensibility to pain: The medical field of anesthesiology requires competency in general medicine, a broad understanding of surgical procedures, and a comprehensive knowledge of clinical obstetrics, chest medicine, neurology, pediatrics, pharmacology, biochemistry, cardiology, and cardiac and respiratory physiology.

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.