A shogun (将軍, shōgun?) listen (literally, "a commander of a force") was one of the (usually) hereditary military dictators of Japan from 1192 to 1867. In this period, the shoguns, or their shikken regents (1203–1333), were the de facto rulers of Japan though they were nominally appointed by the emperor. When Portuguese explorers first came into contact with the Japanese (see Nanban period), they described Japanese conditions in analogy, likening the emperor, with great symbolic authority but little political power, to the Pope, and the shogun to secular European rulers, e.g. the King of Spain. In keeping with the analogy, they even used the term "emperor" in reference to the shogun/regent, e.g. in the case of Toyotomi Hideyoshi, whom missionaries called "Emperor Taicosama" (from Taiko and the honorific sama)
Read more about Shogun.
Some articles on shogun:
... meant the dwelling and household of a shogun, but in time it came to be generally used for the system of government of a feudal military dictatorship ...