broker

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. One that acts as an agent for others, as in negotiating contracts, purchases, or sales in return for a fee or commission.
2. n. A stockbroker.
3. n. A power broker.
4. v. To arrange or manage as a broker: broker an agreement among opposing factions.

Century Dictionary and Cyclopedia

1. n. A middleman or agent who, for a commission or rate per cent. on the value of the transaction, negotiates for others the purchase or sale of stocks, bonds, commodities, or property of any kind, or who attends to the doing of something for another. Brokers are of several kinds, according to the particular branch of business to which their attention is confined, as stock-brokers, exchange-brokers, bill-brokers, cotton-brokers, ship-brokers, etc. See these words.
2. n. One who lends money on pledges, or lets out articles for hire; a pawnbroker, or a lender of goods.
3. n. A pimp or procurer; a pander.
4. n. One who has ‘gone broke’; a ‘dead broke,’ ruined, or bankrupt man.

Wiktionary

1. n. A mediator between a buyer and seller.
2. n. An agent involved in the exchange of messages or transactions.
3. v. To act as a broker; to mediate in a sale or transaction.

GNU Webster's 1913

1. n. One who transacts business for another; an agent.
2. n. An agent employed to effect bargains and contracts, as a middleman or negotiator, between other persons, for a compensation commonly called brokerage. He takes no possession, as broker, of the subject matter of the negotiation. He generally contracts in the names of those who employ him, and not in his own.
3. n. A dealer in money, notes, bills of exchange, etc.
4. n. A dealer in secondhand goods.
5. n. A pimp or procurer.

WordNet 3.0

1. v. act as a broker
2. n. a businessman who buys or sells for another in exchange for a commission