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...球员在备战明天的比赛时带着蔑视对手的情绪。Despite the risk of suspension, he remained defiant.尽管可能会被停职,他仍然桀骜不驯。