One of three carnivorous mammals, also known as polecats, in the family Mustelidae. The European polecat (Mustela putorius) inhabits Europe west of the Ural Mountains; the steppe polecat (M. eversmanni) is found in the steppe zone from Austria to Manchuria and Tibet; and the black-footed ferret (M. nigripes) (see illus.) inhabits the plains region of North America from Alberta and Saskatchewan to northeastern Arizona and Texas. The domestic ferret (M. putorius furo) is generally thought to be a descendant of one or both of the Old World species.