Monopsony

n. condition in which there is one consumer who has a monopoly which enables him to dictate prices and salary

In economics, a monopsony (from Ancient Greek μόνος (monos) "single" + ὀψωνία (opsōnia) "purchase") is a  market form with only one buyer, called "monopsonist," facing many sellers. It is an instance of imperfect competition, symmetrical to the case of a monopoly, in which there is only one seller facing many buyers. The term "monopsony" was first introduced by Joan Robinson[1] (1933). The term "monopsony power", in a manner similar to "monopoly power" is used by economists as a short hand reference to buyers who face an upwardly sloping supply curve but that are not the only buyer; better, but more cumbersome terms may be oligopsony or monopsonistic competition. A monopsonist may be at the same time a monopolist.
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Noun
1. (economics) a market in which goods or services are offered by several sellers but there is only one buyer
(hypernym) market, marketplace
(classification) economics, economic science, political economy

The existence of only one buyer in a market, forcing sellers to accept a lower price than the socially optimal price.