Autocracy is a form of government where the monarch is unlimited by law. The autocrat has uncontrolled and undisputed authority. Its power is maintained through military or police power.
An example of an autocracy is Imperial Russia. Russian government under the tsars was an autocracy extending from the mid-16th century to the early 20th century. An autocracy is distinguished from an oligarchy, in that an oligarchy is a government where the power is shared among a few people.