A "royal princess" refers to a female member of a royal family who holds the title of princess. They are often born into royalty or marry into a royal family. Full definition
Princess Charlotte, at the grand age of 2, has made history by being the first British royal princess to not lose her place in the line of succession upon the birth of a younger male sibling. (nystateofpolitics.com)
In 1348 a 14 year old royal princess, Joan, set out from Portsmouth to marry Pedro of Castile. (itunes.apple.com)
With England's national flower in mind, Beyoncé and Jay - Z (parents of Blue Ivy) would love a floral name that's perfect for a royal princess. (care.com)