A pit bull terrier or a pit bull is a very fierce kind of dog. Some people train pit bull terriers to fight other dogs. 'pit bull a small but extremely strong and sometimes violent fighting dog. or Staffordshire terrier Dog breed developed in 19th-century Britain for fighting other dogs in pits. It was created by crossing the bulldog (which at the time was longer-legged and more agile) with a terrier, possibly the fox terrier. Once known by such names as bull-and-terrier and half-and-half, the pit bull is a stocky, muscular, unusually strong dog with powerful jaws, standing 17-19 in. (43-48 cm) tall and weighing 30-50 lb (14-23 kg). Its stiff, short coat may be any colour, solid or variegated. See also bull terrier