A dictatorship is usually defined as an autocratic form of government in which the government is ruled by a dictator. It has two possible meanings:
Roman dictator was a political office of the Roman Republic. Roman dictators were allocated absolute power during times of emergency. Their power was originally neither arbitrary nor unaccountable, being subject to law and requiring retrospective justification. There were no such dictatorships after the beginning of the 2nd century BCE, and later dictators such as Sulla and the Roman Emperors exercised power much more personally and arbitrarily. In contemporary usage, dictatorship refers to an autocratic form of absolute rule by leadership unrestricted by law, constitutions, or other social and political factors within the state.
For some scholars, dictatorship is a form of government that has the power to govern without consent of those being governed, while totalitarianism describes a state that regulates nearly every aspect of public and private behavior of the people. In other words, dictatorship concerns the source of the governing power (where the power comes from) and totalitarianism concerns the scope of the governing power (what is the government). In this sense, dictatorship (government without people's consent) is a contrast to democracy (government whose power comes from people) and totalitarianism (government controls every aspect of people's life) corresponds to liberalism (government emphasizes individual right and liberty). Though the definitions of the terms differ, they are related in reality as most of the dictatorship states tend to show totalitarian characteristics. When governments' power does not come from the people, their power is not limited and tend to expand their scope of power to control every aspect of people's life.