From the verb brocanter(“to deal in second-hand goods”), of obscure origin. Probably either from Dutchbrok(“piece, fragment”), or from the same root as Middle Frenchbroqueur, abrokeur(“broker”), from Medieval Latin*brocator, abrocator(“broker”), from Old Dutch*brokere(“one who determines the usages of trade, manager”), from broke, bruyck, breuck(“use, usage, trade”), from Proto-Germanic*brūkiz(“use, custom”), from Proto-Indo-European*bhrug-(“to use, enjoy”). More at broker.