• quality of being high, tallness, loftiness; title given to members of a royal family
• you use expressions such as your highness and his highness to address or refer to a prince or princess.
• courtesy title used when referring to a king
his serene highness
• his majesty (courtesy title used when referring to a king)
• any person who is a member of a royal family; title given to members of a royal family; title that was used before 1917 designating any family member (such as brother, sister, child, grandchild, aunt or uncle) who belonged to the male descendant of the royal family (england); title used since 1917 designating child or grandchild of the monarch (england); any person who is given this title by royal family (england)
• your royal highness, his or her royal highness, or their royal highnesses are used to address or refer to members of royal families who are not kings or queens.