Final answer:
A monopoly is a single firm that controls all or nearly all of the supply of a particular good or service in a given market. The definition of the market is crucial in determining whether a firm can be considered a monopoly or not.
Step-by-step explanation:
A monopoly is a single firm that controls all or nearly all of the supply of a particular good or service in a given market. The definition of the market is an important aspect in determining whether a firm can be considered a monopoly. If a firm produces a product without close substitutes, then it can be considered a monopoly producer in a single market. However, if buyers have a range of similar options available from other firms, then the firm is not a monopoly.