An oligarchy (Greek Ὀλιγαρχία, Oligarkhía) (oligocracy) is a form of government in which power effectively rests with a small elite segment of society distinguished by royal, wealth, intellectual, family, military, or religious hegemony. The word oligarchy is from the Greek words for "few" (ὀλίγος olígos) and "rule" (ἀρχή arkhē). Such states are often controlled by politically powerful families whose children are heavily conditioned and mentored to be heirs of the power of the oligarchy.
Oligarchies have been tyrannical throughout history, being completely reliant on public servitude to exist. Although Aristotle pioneered the use of the term as a synonym for rule by the rich, for which the exact term is plutocracy, oligarchy is not always a rule by wealth, as oligarchs can simply be a privileged group. Some city-states from ancient Greece were oligarchies. The combination of the words plutocracy and oligarchy make the word plutarchy. thanks Wikipedia.