an emperor of Russia before 1917 沙皇(1917年以前的俄国皇帝) [as title]Tsar Nicholas II. 沙皇尼古拉斯二世。 ■a South Slav ruler in former times, especially one reigning over Serbia in the 14th century 旧时南斯拉夫人的统治者(尤指14世纪塞尔维亚的统治者) ■[usu. with adj. or noun modifier]a person with great authority or power in a particular area (某领域)权威人士 America's new drug tsar. 美国药界新权威人士。