When there is one buyer and many sellers then that situation is called

In economics, a monopsony (mono: single) is a market form in which only one buyer faces many sellers. It is an example of imperfect competition, similar to a monopoly, in which only one seller faces many buyers. As the only PURCHASER of a good or SERVICE, the monopsonist may dictate terms to its suppliers in the same manner that a monopolist controls the market for its buyers. It is also known as Single buyer RIGHT. A single-payer universal health care system, in which the government is the only buyer of health care services, is an example of a monopsony. Another possible monopsony COULD develop in the exchange between the food industry and farmers.