(n) A female heir who has had sex with one (or both) of her parents. The parents can be kings/queens, presidents, cult leaders, dictators, lords, gods, the pope, buddha, anything/anyone who is of a highest position/rank of their kind.
Princess of Sudetenland: When I grow up I'm going to marry daddy and make more of me because I'm THAT great!
Pedestrian: ...PRINCEST! BURN HER!