A situation where a producer of particular goods or services controls the market, having eliminated all potential or real competitors, or is in possession of a patent to which no other producer has access. The elimination of competition can enable the producer to dictate prices and thereby earn excessive or monopoly profits. The fact that the producer is the major customer for the raw materials often means that potential competitors can be prevented om obtaining supplies of those materials; this strengthens the producer's control. Monopolies are usually unacceptable in democratic societies and legislation generally exists to keep them in check. The U.S.A. has its anti-trust laws. Germany has legislation against cartels and in the U.K. the system is regulated by the Monopolies and Mergers Commission.

Reference: The Penguin Business Dictionary , 3rd edt.