middleman in WordNet English dictionary

1. a person who is in a position to give you special assistance
   "he used his business contacts to get an introduction to the governor"
   contact  middleman 
   
2. the performer in the middle of a minstrel line who engages the others in talk
   interlocutor  middleman 
   
3. someone who buys large quantities of goods and resells to merchants rather than to the ultimate customers
   jobber  middleman  wholesaler