noun
1.
a. : a child, brother, sister, uncle, aunt, or grandchild in the male line of the British sovereign — used as a title before 1917
b. : a child or grandchild of the British sovereign — used as a title since 1917
c. : someone on whom the British sovereign chooses to bestow the designation
d. : any of various members of imperial and royal families of other countries
2. : a person properly addressed as Royal Highness
eight royal highnesses attended the coronation