Knyaz

In Serbo-Croatian and some West Slavic languages, the word has later come to denote "lord", and in Czech, Polish and Slovak also came to mean "priest" (kněz, ksiądz, kňaz) as well as "prince/duke" (knez, kníže, książę, knieža).

The proto-Slavic form was *kъnędzь, kŭnędzĭ;[7] Church Slavonic: кънѧѕь,[8] kŭnędzĭ; Bulgarian: княз, knyaz; Old East Slavic: князь, knyazĭ; Polish: książę; Serbo-Croatian Latin: knez / Serbo-Croatian Cyrillic: кнез; Czech: kníže; Slovak: knieža; etc.

[3][9] The rulers of the Duchy of Poland bore the title of książę, which was rendered as dux or princeps in Latin, and later adopted krol (from Karl, the name of Charlemagne) and its equivalent rex following Bolesław I's coronation in 1025.

Later, with the development of feudal statehood, it became the title of a ruler of a state, and among East Slavs (Russian: княжество (knyazhestvo), Ukrainian: князівство, romanized: kniazivstvo) traditionally translated as duchy or principality, for example, of Kievan Rus'.

[14][15][16] According to Florin Curta, the primary sources have a variety of names for the rulers of the Bulgars before christianisation - such as including ‘rex’, ‘basileus’ and ‘khagan’.

He ruled a Russian: Великое Княжеcтво, romanized: Velikoye Knyazhestvo or Ukrainian: Велике Князiвcтво, romanized: Velyke Knyazivstvo (Grand Duchy), while a ruler of its vassal constituent (udel, udelnoe knyazivstvo or volost) was called udelny knyaz or simply knyaz.

From the mid-18th century onwards, the title Velikii Kniaz was revived to refer to (male-line) sons and grandsons of Russian Emperors.

Following the union of the Kingdom of Poland and the Grand Duchy of Lithuania, kniaź became a recognised title in the Polish-Lithuanian Commonwealth.

In parts of Serbia and western Bulgaria, knez was the informal title of the elder or mayor of a village or zadruga until around the 19th century.