mid-14c. (mid-13c. in surnames), commercial agent, factor, also an agent in sordid business, from Anglo-Frenchretailer of wine, tapster; perhaps from Portuguesebarter, but more likely from Old Frenchto broach, tap, pierce (a keg), from) pointed tool (seebroach(n.)), with an original sense of wine dealer, hence retailer, middleman, agent. In Middle English, used contemptuously of peddlers and pimps, one who buys and sells public office (late 14c. in Anglo-French), intermediary in love or marriage (late 14c.).
to act as a broker, 1630s (implied inbrokering), frombroker(n.). Related:Brokered.