Properly speaking, is one who sells refuse. In German, called mäklers, that is, “sellers of damaged stores.” (Teutonic, brak or wrak, refuse, allied with German brauchen.)
Generally some special word is prefixed as bill-broker, cotton-broker, ship-broker, stock-broker, etc.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894
More on Broker from Infoplease: