You're probably familiar with the word monopoly, but you may not recognize its conceptual and linguistic relative, the much rarer oligopsony. Both monopoly and oligopsony are ultimately from Greek, although monopoly passed through Latin before being adopted into English. Monopoly comes from the Greek prefix mono-, which means "one," and pōlein, "to sell." Oligopsony derives from the combining form olig-, meaning "few," and the Greek noun opsōnia—"the purchase of victuals"—which is ultimately from the combination of opson, "food," and ōneisthai, "to buy." It makes sense, then, that oligopsony refers to a buyer's market in which the seller is subjected to the potential demands of a limited pool of buyers. Another related word is monopsony, used for a more extreme oligopsony in which there is only a single buyer.