The term 'Royal Highness' is a title of nobility given to members of a royal family. It is used as a form of address for a prince or princess, and is also used to refer to the spouse of a monarch. The title is typically abbreviated to 'HRH' and is usually followed by the name of the person it is being addressed to. In crossword puzzles, the title is often represented by the abbreviations 'HER' and 'HIS', which stand for 'Her Royal Highness' and 'His Royal Highness' respectively.