Tsarevna was a title given to the daughters of tsars in Russia before the 18th century. The male equivalent was tsarevich.
Painting of a tsarevna by Vasily Surikov
Tsar is a Slavic title derived from the Latin word caesar, which was intended to mean "emperor" in the European medieval sense of the term—a ruler with the same rank as a Roman emperor, holding it by
Tsarevna
…Tsarevna (Russian: царевна, IPA: ) was a title given to the daughters of tsars in Russia before the 18th century. The male equivalent was tsarevich. All of them died unmarried with the exception of the daughters of Ivan V. Notably…
Simeon I of Bulgaria, the first Bulgarian tsar and the first person who bore the title "tsar", by Alphonse Mucha
Reception of the Tsar of Russia in the Moscow Kremlin, by Ivan Makarov
Crowning of Stefan Dušan, Emperor of the Serbs, as tsar, by Paja Jovanović
Mostich's epitaph uses the title tsar (outlined): "Here lies Mostich who was ichirgu-boil during the reigns of Tsar Simeon and Tsar Peter. At the age of eighty he forsook the rank of ichirgu boila and all of his possessions and became a monk. And so ended his life." (Museum of Preslav)