Royal Highness
noun uk/ˌrɔɪ.əl ˈhaɪ.nəs/ us/ˌrɔɪ.əl ˈhaɪ.nəs/
Her/His/Your Royal Highness （对王室成员的尊称）殿下
used when you are speaking about or to a royal person
Thank you, Your Royal Highness. 多谢殿下。
His Royal Highness the Prince of Wales 威尔士亲王殿下