counterparty

[ koun-ter-pahr-tee ]
/ ˈkaʊn tərˌpɑr ti /

noun, plural coun·ter·par·ties. Finance.

the other person or institution entering into a financial contract or transaction: the default of a counterparty.
Also con·tra·par·ty [kon-truh-pahr-tee] /ˈkɒn trəˌpɑr ti/.

Origin of counterparty

1980–85; counter- + party (in the legal sense “a signatory”)

British Dictionary definitions for contraparty

counterparty
/ (ˈkaʊntəˌpɑːtɪ) /

noun plural -parties

a person who is a party to a contract