Shogun: The title for a military commander in ancient Japan (8th century to 12th century A.D.), and later for a ruler of Shogunate Japan (12th century to 1868).
A shogun is essentially a military general. During the Shogunate period, however, the emperor of Japan was a mere figurehead, while the shogun wielded actual power over the country. The shoguns lost power after the Meiji Restoration in 1868.
The word "shogun" comes from the Japanese words sho, meaning "commander," and gun, or "troops."