oligarchyol·i·gar·chy /ˈɒləgɑːkiˈɑːləgɑːrki, ˈoʊ-/ noun (plural oligarchies)1[uncountableU] when a country is ruled or controlled by a small group of people, usually from the same social classOligarchy took over from democracy.
2[countableC] a country, organization, industry etc controlled by a small group of people, or the group who control itThe industry is dominated by an oligarchy of three oil companies.
—oligarch noun [countableC]the changing alliances of Russia’s corporate oligarchs
—oligarchic (also oligarchical) adjectiveadjthe dominance of a small oligarchical group of businessmen