breed of terrier known for its muscular athleticism and fiery courage; coat is short, flat, and glossy and may be almost any color but most often is pure white with black eye patch; ears close together and usually stiffly erect; tail medium-length and held horizontally away from body; eyes are very dark and have a piercing glint; adult stands 10–14 in. (25–36 cm) tall at shoulders and weighs 22–32 lbs (10–15 kg); originated in Great Britain as a fighting dog.