What is the meaning of the term fullblood?

If you were breeding animals, full-blood means that both parents are of the same breed. "He's a full-blood Arabian stallion" means that both his parents are Arabians. "She's a full-blood dachshund" means that both of her parents are dachshunds. For people who like to think of human beings as the same as animals, similar remarks can be made about people whose parents are the same breed or race.