The term 'Russian Ruler of Old' refers to two different titles: CZAR and TSAR. CZAR is a title derived from the Latin word Caesar, which was used by the Roman emperors. It was adopted by the rulers of Russia in the 16th century and was used until the Russian Revolution in 1917. TSAR is a variation of the word CZAR and was used interchangeably with it. Both titles refer to the same position, that of an absolute monarch who ruled over the Russian Empire.