Obdurate

obdurate.
adjective. Stubbornly refusing to change one's opinion or course of action.

Growing up, Laura became accustomed to hearing the word "no." She routinely asked her father for all sorts of things, assuming that it wouldn't hurt to ask: a dog, a horse, a trip to Disneyland, permission to go to a sleepover thirty minutes before it was scheduled to begin.... His response was negative so often that it became the default in her mind.

She learned before she started kindergarten that it did no good to plead with him to change his decision. Once his mind was made up, it was as obdurate as diamond. No amount of wheedling or whining, tears or appeals to her mother for her intervention would affect him. As for her mother, she was almost as stubborn as her husband. Laura became more crafty as she grew older, and knew that asking her mother's permission first sometimes yielded results, but only sometimes. Usually, her response was, "Wait until your father gets home and ask him." Laura knew without pursuing that option what the result would be. If Mom was uncertain enough to make that statement, Dad's answer would almost certainly be "No."

Definitions adapted from The New Oxford American Dictionary, Oxford University Press, Inc., 2005 (eBook Edition, copyright 2008), and from Webster's Seventh New Collegiate Dictionary, G. & C. Merriam Company, Publishers, Springfield, Massachusetts, USA, 1965, depending on which is more convenient to hand.