Kniaginia

Dashkova, E. R. (Ekaterina Romanovna), kniaginia, 1743–1810.

Source: wiktionary

The main characters are adapted to the new locale: the Russian Kniaz is replaced with Prince Ianysh, the Kniaginia with the Czech Princess Lubusia, Natasha with a neighborhood beauty Eliza, and Rusalka with Vodaniza (from voda, water), who “rules over all rivers and lakes.”

Source: wiktionary

In the year 1125, the kniaginia, Sviatopolk’s wife, died on February 28.

Source: wiktionary

Thus, as there were multiple male rulers in Rus at one time bearing the title of kniaz’, there were also multiple female rulers in Rus at one time, bearing the title of kniaginia.

Source: wiktionary