Overview
Princess is a title used by a female member of a monarch's family or by a female ruler. The male equivalent is a prince (from Latin princeps, meaning principal citizen). Most often, the term has been used for the consort of a prince, or for the daughter of a monarch. A crown princess can be the heir apparent to the throne or the heir apparent's spouse.
Princess as a substantive title
Some princesses are reigning monarchs of principalities. There have been fewer instances of reigning princesses than reigning princes, as most principalities excluded women from inheriting the throne. An example of a princess regnant is Constance of Antioch, princess regnant of Antioch in the 12th century. Since the president of France, an office for which women are eligible, is ex-officio a co-prince of Andorra, then Andorra could theoretically be jointly ruled by a princess.
Princess as a courtesy title
Descendants of monarchs
For many centuries, the title "princess" was not regularly used for a monarch's daughter, who, in English, might simply be called "Lady". Old English had no female equivalent of "prince", "earl", or any other royal or noble title aside from queen. Royal women were simply addressed or referred to as "The Lady [Firstname]". For example, Mary and Elizabeth, daughters of Henry VIII of England, were often simply referred to as "the Ladies Mary and Elizabeth". This practice, however, was not consistent. In the marriage contract between Prince George of Denmark and Anne, daughter of James II of England, Anne is referred to as "The Princess Anne".
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