A market with one buyer can push wages down just like a monopoly pushes prices up

A monopsony is the mirror image of a monopoly: instead of one seller controlling a market, a single dominant buyer does, giving it power to push down what it pays. Economist Joan Robinson coined the term in 1933, originally picturing a literal 'company town' with one major employer, but modern research finds weaker versions of monopsony power common even in ordinary labor markets, wherever switching jobs is costly enough to leave workers with limited real alternatives.

— Joan Robinson, Monopsony — The Economics of Imperfect Competition, 1933