In political science, despotism (despotismós) is a form of government in which a single entity rules with absolute power. Normally, that entity is an individual, the despot; but (as in an autocracy) societies which limit respect and power to specific groups have also been called despotic.
Colloquially, the word despot applies pejoratively to those who use their power and authority to oppress their populace, subjects, or subordinates. More specifically, the term often applies to a head of state or government. In this sense, it is similar to the pejorative connotations that are associated with the terms tyrant and dictator.
The root despot comes from the Greek word despotes, which means "one with power." In ancient Greek usage, a despótès was technically a master who ruled in a household over those who were slaves or servants by nature. The term has been used to describe many rulers and governments throughout history. It connoted the absolute authority and power exercised by the pharaohs of Ancient Egypt, signified nobility in Byzantine courts, designated the rulers of Byzantine vassal states, and acted as a title for Byzantine emperors. In this and other Greek or Greek influenced contexts, the term was used as an honorific rather than as a pejorative.
Due to its reflexive connotation throughout history, the word despot cannot be objectively defined. While despot is closely related to other Greek words like basileus and autokrator, these connotations have also been used to describe a variety of rulers and governments throughout history, such as local chieftains, simple rulers, kings, and emperors.
Of all the ancient Greeks, Aristotle was perhaps the most influential promoter of the concept of oriental despotism. He passed this ideology to his student, Alexander the Great, who conquered the Achaemenid Empire, which at the time was ruled by the despotic Darius III, the last king of the Achaemenid dynasty. Aristotle asserted that oriental despotism was not based on force, but on consent.