A physician; a member of the medical profession; one who is trained and licensed to heal the sick or injured. William S. Haubrich adds, "In years past, 'doctor' was a title of courtesy and respect bestowed on any learned man. Later, it became associated with the title of the highest academic degree [e.g., Ph.D.]. Meanwhile, 'doctor' acquired a specifically medical connotation. Probably this was because, of all learned scholars, only members of the medical faculty became familiar to the public at large."