Definition of "bullheaded"

“I know, my dear. I’ve lived with these bullheaded Sartorises for eighty years, and I’ll never give a single ghost of ’em the satisfaction of shedding a tear over him. What did Horace’s message say?”

1964 , William Faulkner, Sartoris (The Collected Works of William Faulkner), London: Chatto & Windus, page 23