border terrier, breed of hardy, medium-sized terrier developed in the Border districts of N England in the 18th and 19th cent. It stands about 12 in. (30 cm) high at the shoulder and weighs from 131/2 to 151/2 lb (6.1–6.9 kg). Its weather-resistant double coat is composed of a short, dense underlayer and a close-lying, very wiry topcoat. It may be red, grizzle and tan, blue and tan, or wheaten in color, occasionally with a small amount of white on the chest. The border terrier was bred to hunt and kill the large hill fox of its native Border districts and came to be used against a wide variety of vermin. Raised today chiefly as a pet, it is a relatively rare breed in the United States. See dog.