2019-5-19 · broker (plural brokers) . A mediator between a buyer and seller.; A stockbroker.; A mediator in general, one who liaises between two or more parties to attempt to achieve an outcome of some kind.. 2014, Spencer C. Tucker, World War I: The Definitive Encyclopedia and Document Collection, →ISBN, page 244 The peace plan was representative of Benedict's inability to appear as a neutral broker of ...