mo·nop·so·ny 
(mə-nŏpsə-nē)
(mə-nŏpsə-nē)n. pl. mo·nop·so·nies
A market situation in which the product or service of several sellers is sought by only one buyer.
[MON(O)- + Greek opsōniā, purchase of food; see DUOPSONY.]
mo·nopso·nist n.
mo·nop′so·nistic adj.