Princess of Orange

Princess of Orange is the title ("name") used for the women who were married to the Ruling Princes of Orange in the time between 1171 to 1815. Since 1815, it was also used for the wives of the heirs to the Dutch throne, who were titled Prince of Orange. The only woman who became a "Princess of Orange" without being married to a "Prince of Orange" was Marie, Princess of Orange (1393-1417). Together with her husband John, Prince of Orange (1393-1418), they governed the land. 
Because the title "Prince of Orange" was only used for 'the eldest son of the King' (the "crown prince"), Dutch crown princesses did not get the title. There were no "oldest sons" for a few generations, and so the title was not used since 1877. Because Dutch law was changed in 1983 to include "oldest daughters of the King", Catharina-Amalia, the next Princess of Orange became the first Dutch Princess of Orange in her own right once her father, Prince Willem-Alexander, became King of the Netherlands.