In medicine, a surgeon is a specialist in surgery. Surgery is a broad category of invasive medical treatment that involves the cutting of a body, whether that of a human or other animal, for a specific reason such as the removal of diseased tissue or to repair a tear or breakage.
In the U.S., surgeons train for longer than other specialists; only after 9 years of training do they qualify. These years include 4 years of medical school and a minimum of 5 years of residency.
In modern English, the term physician is used in two main ways, with relatively broad and narrow meanings respectively. This is the result of history and is often confusing. These meanings and variations are explained below.