in the trading sense, "contractor, negotiator, broker," especially "one who buys merchandise in bulk and sells it in smaller quantities to retailers or other traders," 1795, from middle (adj.) + man (n.). From mid-15c. as the name of some type of workman in wire-making. From 1741 as "one who takes a middle course." In minstrel shows, "the man who sits in the middle of the semicircle of performers and leads the dialogue between songs," by 1870.