1. A situation in which one company controls an industry or is the only provider of a product or service: "A monopoly is an extreme situation that is used in capitalism and by many governments because most people believe that, with few exceptions, the system just doesn't work when there is only one provider of a product or service because there is no incentive to improve it so it will meet the demands of consumers."

By definition, monopoly is characterized by an absence of competition; which sometimes results in high prices and inferior products."

2. A product or service whose supply is controlled by only one company and which has an exclusive control of a commodity or service in a particular market or a control that makes possible the manipulation of prices: "Several governments attempt to prevent commercial monopolies from existing through the use of antitrust laws.
3. In law, a legal right to the exclusive control of an industry or service, as granted by a government: "A situation in which a single company or group owns all or nearly all of the market for a given type of product or service."

"Public monopolies are set up by governments to provide essential services; such as, water, electricity, police services, garbage collecting, etc.; so, in such cases, a monopoly is probably more effcient than an oligopoly or multiopoly would be."

4. A law or a situation in which one supplier or producer controls over one third of a market: "Naturally, there are gray areas which take, for example, the granting of patents on new inventions. These provide a monopoly on a product for a set period of time."

"The reasoning behind patents is to give innovators some time to recoup what are often large research and development costs. In theory, they are a way of using monopolies to promote innovation."