Which term is used to describe the market condition of having only one seller?

The term that describes the market condition of having only one seller is a monopoly. In a monopoly, a single firm dominates the entire market, meaning it is the sole provider of a particular product or service. Because there are no alternative sources for consumers, the monopolist has significant control over the market price and the supply of goods. This market structure often leads to higher prices and less innovation compared to markets with more competition, as the monopolist faces little to no competitive pressure.

In contrast, oligopoly refers to a market structure where a few firms dominate, while perfect competition consists of many sellers offering identical products. A competitive market generally implies multiple buyers and sellers, fostering competition that can lead to more favorable prices and choices for consumers.