Tsar or czar (Russian, Bulgarian, Serbian: цар, in scientific transliteration respectively car' and car), occasionally spelled csar or tzar in English (Zar in German and most other Germanic languages, Çar in Turkish), is a Slavonic term designating certain monarchs.
Originally, the title tsar (derived from Caesar) meant Emperor in the European medieval sense of the term, that is, a ruler who has the same rank as a Roman or Byzantine emperor (or, according to Byzantine ideology, the most elevated position adjacent to the one held by the Byzantine monarch) due to recognition by another emperor or a supreme ecclesiastical official (the Pope or the Ecumenical Patriarch).
Occasionally, the word could be used to designate other, non-Christian, supreme rulers. In Russia and Bulgaria the imperial connotations of the term were blurred with time and, by the 19th century, it had come to be viewed as an equivalent of King.
"Tsar" was the official title of the supreme ruler in the following states:
- Bulgaria in 913–1018, in 1185–1422 and in 1908–1946
- Serbia in 1346–1371
- Russia from about 1547 until 1721 (after 1721 and until 1917, the title was used officially only in reference to the Russian emperor's sovereignty over certain formerly independent states such as Poland and Georgia).
- czar. The American Heritage® Dictionary of the English Language: Fourth Edition. 2000
- The Brockhaus and Efron Encyclopedia entry on Tsar. Retrieved on 2006-07-27.
- The entry on tsar in the Eleventh Edition of Encyclopædia Britannica (1911).
- Български тълковен речник. 3. изд. (the entry on цар in A Bulgarian explanatory dictionary).
- Словарь современного русского литературного языка. Издательство Академии наук СССР. 1948-1965 (the entry on царь in The dictionary of the modern Russian literary language)