That ornery horse that keeps heading back to the barn, no matter how much you coax and pull and try to convince him to stay on the trail? He's showing you his contumacious side, meaning he's stubbornly resisting authority.
You might hear the word contumacious used in a courtroom to describe an uncooperative witness or someone who willfully disobeys an order given by the court. If you have a glove compartment full of unpaid parking tickets, when you finally land in court your disobedient behavior may cause the judge to tell you that you're a contumacious lout. You'll not only have to pay the tickets, you'll also be slapped with a big fine, and you'll never be contumacious again.