The branch of medicine that deals with the diagnosis and treatment of injury, deformity, and disease by manual and instrumental means. A surgical operation or procedure, especially one involving the removal or replacement of a diseased organ or tissue. An operating room or a laboratory of a surgeon or of a hospital's surgical staff. The skill or work of a surgeon. Chiefly British A physician's, dentist's, or veterinarian's office. Chiefly British The period during which a physician, dentist, or veterinarian consults with or treats patients in the office.