Oligopsony

Restrictive market structures
Quantity one two few
Sellers Monopoly Duopoly Oligopoly
Buyers Monopsony Duopsony Oligopsony

An oligopsony (from Greek ὀλίγοι (oligoi) "few" and ὀψωνία (opsōnia) "purchase") is a market form in which the number of buyers is small while the number of sellers in theory could be large. This typically happens in a market for inputs where numerous suppliers are competing to sell their product to a small number of (often large and powerful) buyers. It contrasts with an oligopoly, where there are many buyers but few sellers. An oligopsony is a form of imperfect competition.

The terms monopoly (one seller), monopsony (one buyer), and bilateral monopoly have a similar relationship.