If you say that someone is defiant, you mean they show aggression or independence by refusing to obey someone.
例句
The players are in defiant mood as they prepare for tomorrow's game...球員在備戰明天的比賽時帶著蔑視對手的情緒。Despite the risk of suspension, he remained defiant.盡管可能會被停職，他仍然桀驁不馴。