【Monopoly】 , 【corner】 ,  【pool】 ,  【syndicate】 ,  【trust】 ,  【cartel】  are comparable rather than synonymous terms when they apply to a means of controlling prices.

【Monopoly】  denotes the exclusive control of a service (as telephone or telegraph service) or traffic (as transportation of goods and passengers by railroad) or of a commodity (as wheat or petroleum) in a given market.  【Monopoly】 may imply exclusive control created by the state (as by franchise or patent or copyright). More frequently, however, the term is used to imply exclusive power to buy or sell a commodity or service in a given market, especially as a result of ownership or control of the sources of supply (as mines) or of the available stock of a commodity.

In extended use  【monopoly】 also denotes the group or organization having such control.

A temporary or local 【monopoly】 (as of a particular security on a stock exchange or of a particular commodity on a produce exchange) constitutes a  【corner】 , so called because it puts all those who are determined to buy into a 【corner】 , or position where they must pay the price asked.

【Pool】  in this relation applies primarily to a combination of property, or of interests of different persons or companies, by means of which a more or less permanent control or 【monopoly】 is acquired. Distinctively, however,  【pool】  implies a joint undertaking or end which cannot be attained unless the market is managed either by manipulating prices (as of a commodity or security) or by destroying the effects of competition (as through agreements concerning prices or rates, regulation of outputs, or division of earnings of each organization concerned).

【Syndicate】  is applied chiefly to a group of individuals, firms, or corporations (as banking houses) which organize for a limited time to accomplish a given purpose or more specifically such a group that is organized to market an issue of a security, makes its profit from the difference between the agreed-upon sum advanced to the issuing corporation for the securities and the fixed sale price at which they are marketed, assumes responsibility for absorbing any surplus securities not marketed, and dissolves when the marketing period is completed. Outside of the field of finance, the use of the term is extended in its application to any combination (as of newspapers, business concerns, or criminals) interested in a common project or enterprise, and often implies relation to a 【monopoly】 .

【Trust】  specifically applies to a merger in which stockholders in the merged corporations exchange their stock for 【trust】 certificates in the new corporation and surrender their rights to trustees who operate the combined corporations, but  【trust】  is often extended to any combination of business entities, especially when felt to represent a threat to healthy competition.

【Cartel】  implies an international combination for controlling production and sale of a product or group of products.