Knyaz or knez, also knjaz, kniaz is a historical Slavic title, used both as a royal and noble title in different times of history and different ancient Slavic lands. It is usually translated into English as prince, depending on specific historical context and the potentially known Latin equivalents of the title for each bearer of the name. These translations probably derive from the fact that the title tsar was often treated as equivalent to "king" by European monarchs. In Latin sources the title is usually translated as princeps, but the word was originally derived from the common Germanic *kuningaz (king).
Until Boris I (852–889) the title of the Bulgarian monarchs was knyaz (Кнѣзъ). His son, Simeon I (893–927), adopted the title tsar (emperor), which became the title of the subsequent Bulgarian rulers.
The title knez appeared in the early 12th-century Glagolitic Baška tablet inscription, found on the island of Krk, Croatia.
Kneaze Alexey Michailovitz, 1664 (Tsar Alexis I of Russia)
A prince is a male ruler or a male member of a monarch's or former monarch's family. Prince is also a title of nobility, often hereditary, in some European states. The female equivalent is a princess. The English word derives, via the French word prince, from the Latin noun prīnceps, from primus (first) and caput (head), meaning "the first, foremost, the chief, most distinguished, noble ruler, prince".
Louis de Bourbon, Prince de Condé, was the premier prince du sang during his lifetime (painted by Joost van Egmont).
José, Prince of Brazil, Duke of Braganza, died before he could ascend to the throne of Portugal.
Coat of arms of the princes Sanguszko-Lubartowicz (Poland).
Coat of arms of the princes Youssoupoff