ETYM Latin monopolium, Greek; monos alone + polein to sell.
(Economics) A market in which there are many buyers but only one seller.
In economics, the domination of a market for a particular product or service by a single company, which therefore has no competition and can keep prices high. In practice, a company can be said to have a monopoly when it controls a significant proportion of the market (technically an oligopoly).
In the us, antitrust legislation has been used vigorously to break up and/or prevent the growth of monopolies. Even some closely regulated monopolies, such as the American Telegraph and Telephone Company, have been broken up to ensure competition. A monopsony is a situation in which there is only one buyer; for example, most governments are the only legal purchasers of military equipment inside their countries.
Exclusive control or possession of something.

(Trademark) A board game in which players try to gain a monopoly on real estate as pieces advance around the board according to the throw of a die.
The world's biggest-selling copyrighted game, a board game of buying properties, building houses on them, and charging rent.
It was devised in the US 1934 by Charles B Darrow (1889–1967), with street names from Atlantic City, New Jersey, where he spent his vacations; he sold the game 1935 to Parker Brothers, US game manufacturers, for a royalty.