Royal family
A royal family was a group of royals who were related by blood or marriage. One notable royal family was the Royal Family of Luria. (DS9: "Who Mourns for Morn?")
In 2268, after Elaan berated James T. Kirk for daring to touch her, a member of the royal family of Elas, he replied that he only did so in self-defense. She then warned him that the punishment for his actions was death, but he explained that because they were not on Elas, but rather the USS Enterprise, he was in charge, not her. (TOS: "Elaan of Troyius")