Modern Princesses Of Europe

For many centuries, the title "princess" was not regularly used for a monarch's daughter, who might simply be called "Lady" or a non-English equivalent; Old English had no female equivalent to "prince", "earl", or any royal or noble aside from the queen, and the women of nobility bore the title of "Lady".
As women have slowly gained more autonomy through European history, the title of princess has become simply the female counterpart of prince and does not necessarily imply being controlled or owned by a prince. In some cases then, a princess is the female hereditary head of state of a province or other significant area in her own right. The ancient meaning applies in Europe still to the extent that a female commoner who marries a prince will almost always become a princess, but a male commoner who marries a princess will almost never become a prince, unless his wife has, or is expected to attain, a higher title, such as Queen regnant. The implication is that if the man held the equivalent masculine title, he would have rank over his wife without the necessary pedigree.