A *broker who deals in *commodities, especially one who trad es on behalf of principals in a *commodity market (see also FUTURES CONTRACT). The rules governing the procedure adopted in each market vary from commodity to commodity and the function of brokers may also vary. In some markets brokers pass on the names of their principals,- in others they do not, and in yet others they are permitted to act as principals. Commodity brokers. other than those dealing in metals, are often called produce brokers.