Tsarism is a way of running a country where one man, the tsar, holds all the power — above all, the system Russia lived under until 1917. The -ism at the end tells you this is not one person but a whole arrangement: the tsar at the top, the church supporting him, nobles owning the land, no elected parliament worth the name, and ordinary people with very little say. When someone says 'tsarism collapsed', they do not mean one man fell over; they mean the entire structure came apart. The word is nearly always used with a frown. Historians and writers reach for it when they want to point at the unfairness and the heaviness of that system, so it carries a judgement inside it in a way that 'the tsar's government' does not. You will meet it most in history books and political writing, and it can also stretch beyond Russia — a writer might call some other country's rule 'a kind of tsarism' to say it is one-man rule dressed up. That stretched use is not common in everyday talk. The spelling 'czarism' appears in older books and is the same word.

沙皇專制（制度）、沙皇統治。注意是「制度」不是「某位沙皇」，中文寫成「沙皇制度」比「沙皇」更貼。