Царь
A
Russian title somewhere between
King and
Emperor, and the main official title of the
monarchs of Russia between 1547 and 1721. In that year the westernizing Tsar
Peter the Great was elevated to the title of
Imperator, Emperor, and
Tsar was used as a lesser title for some of his other territories.
The title was also used in the mediaeval empire and later independent kingdom of Bulgaria (1908-1946) and for the mediaeval emperor of Serbia, Car Stefan Dušan. It is in general the Slavonic equivalent for 'emperor': so Constantinople was called Tsarigrad among the neighbouring Slavs.
The wife of a Tsar, or a female Tsar reigning in her own right, was a Tsarítsa, though in Western languages the non-Russian form Tsarina also occurs. The eldest son and heir of the Tsar was the Tsesarévich; any son of the Tsar was a Tsarévich, and a daughter or daughter-in-law was a Tsarévna. These are of course also seen in other spellings with Cz or Tz instead of the Ts, but Ts best reflects the Russian letter Ц.
The royal title between 1547 and 1721 was comparatively modest: they were styled as e.g. "By the Grace of God Great Sovereign Tsar and Grand Prince, Peter I, of All Russia, Autocrat" (where knyaz = prince and samodyerzhets = autocrat). The first such tsar was Ivan IV (Ivan the Terrible); before that they had been Grand Princes of various states based on cities, most recently Moscow.
From 22 September 1721 he and his successors rejoiced in being e.g. "By the grace of God, Peter I, All-Russian Emperor and Autocrat of Moscow, of Kiev, Vladimir, Novgorod; Tsar of Kazan, Tsar of Astrakhan, Tsar of Siberia; Lord of Pskov; Grand Prince of Smolensk; Prince of Estonia, Livonia, Courland, Tver, Yugoria, Perm, Vlatsk, Bulgaria, and of other lands; Lord and Grand Prince of Lower Novgorod, Chernigov, Ryazan, Rostov, Yaroslav, Byelozersk, Udoria, Obdoria, Kondia, and all the Northern Region; Lord and Sovereign of the lands of Imeretia, Kartlia, Kabardinia; Lord of the Circassian and Mountain princes and of other lands".
In 1906 the peasants were fuming, if not outright revolting, the Great War and the Revolution were a few short years away, so it was a splendid time to upgrade the imperial titles to something really striking and bring it up to date with political realities. From 6 May 1906 the imperial style was "By the grace of God, Nicholas II, All-Russian Emperor and Autocrat of Moscow, Kiev, Vladimir, Novgorod; Tsar of Kazan, Tsar of Astrakhan, Tsar of Poland, Tsar of Siberia, Tsar of the Chersonnese Taurics, and Tsar of Georgia; Lord of Pskov; Grand Prince of Smolensk, Lithuania, Volhynia, Podolia and Finland; Prince of Estonia, Livonia, Courland and Semigallia, Samogitia, Bialystok, Karelia, Tver, Yugoria, Perm, Vlatka, Bulgaria, and of other lands; Lord and Grand Duke of Lower Novgorod, Chernigov, Ryazan, Polotsk, Rostov, Yaroslav, Byelozersk, Udoria, Obdoria, Kondia, Vitebsk, Mstislav, and all the Northern Region; Lord and Sovereign of the lands of Imeretia, Kartlia, Kabardinia and the provinces of Armenia; Lord of the Circassian and Mountain princes; Lord of Turkestan; Heir of Norway; Duke of Schleswig-Holstein, Stormarn, Ditmarschen and Oldenburg, and so on, and so on, and so on".
Full grand titles from www.worldstatesmen.org/Russia.htm -- see which for the exact forms in Russian