oligopoly UK /ɒlɪˈɡɒpəli/US /ˌɑləˈɡɑpəli/ noun1 •An economic condition in which a small number of sellers exert control over the market of a commodity.Because of the ease of collusion, particularly price fixing, duopolies and oligopolies easily produce outcomes as bad for the general public as outright monopolies. formsoligopolies