highness/ˈhaɪnɪs; `haɪnɪs/ n[C](usu 通常作 Highness) title used in speaking to or of a member of the royal family 殿下, 阁下（用作对皇室成员的尊称） His/Her/Your Royal Highness 殿下（或阁下） Their Royal Highnesses the Duke and Duchess of Kent 肯特公爵和公爵夫人阁下.
牛津英汉双解词典