LINK / CITE ADD TO WORD LIST. noun. The definition of an oligarchy is a government structure where a small and elite group have power. 1  An example of an oligarchy is a society in which a small group of dictators is in charge of the country.2  The dictators themselves are also an example of an oligarchy.INK / CITE ADD TO WORD LIST. noun. The definition of an oligarchy is a government structure where a small and elite group have power. 1  An example of an oligarchy is a society in which a small group of dictators is in charge of the country.