Tsar (
Old Church Slavonic: ц︢рь (usually written thus with a
titlo) or цар, цaрь; also
Czar or
Tzar in Latin alphabet languages) is a
title used to designate certain European
Slavic monarchs or supreme rulers. As a system of government in the
Tsardom of Russia and
Russian Empire, it is known as
Tsarist autocracy, or Tsarism. The term is 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, with-holding it by the approval of another emperor or a supreme ecclesiastical official (the
Pope or the
Ecumenical Patriarch)—but was usually considered by western Europeans to be equivalent to king, or to be somewhat in between a royal and imperial rank.