pit bull terrier Definition

a muscular, short-haired, stocky dog (such as an American pit bull terrier or American Staffordshire terrier) of any of several breeds or a hybrid with one or more of these breeds that was originally developed for fighting and is noted for strength, stamina, and tenacity

an aggressive and tenacious person

any of a breed of muscular, agile dogs that have a short, smooth coat, were developed to combine the traits of terriers and bulldogs, have extremely powerful jaws and great strength and tenacity, and that were originally bred for dog fighting —called also pit bull terrier