What term describes an individual, organization, or company that holds significant market share and can influence prices?

The term that best describes an individual, organization, or company that holds significant market share and can influence prices is "monopoly." A monopoly occurs when a single entity is the exclusive provider of a product or service in a market, thus controlling the market entirely. In such situations, the monopolistic entity can set prices without competition, as consumers have no alternative sources for the good or service. This level of control often leads to higher prices and limits consumer choices, illustrating how a monopoly operates within an economic context.

In contrast, a cartel refers to a group of independent market participants who collude to improve their profits and control prices, rather than being a singular entity. An oligopoly describes a market structure where a few firms dominate, and while they can influence prices collectively, they do not have the same level of control as a monopoly. A conglomerate, on the other hand, refers to a company that owns diverse businesses across various industries, which does not inherently indicate significant control over a single market.