The Collaborative International Dictionary of English v.0.48:

Bargain \Bar"gain\, v. t. [imp. & p. p. Bargained (?); p. pr.
   & vb. n. Bargaining.]
   To transfer for a consideration; to barter; to trade; as, to
   bargain one horse for another.
   [1913 Webster]

   To bargain away, to dispose of in a bargain; -- usually
      with a sense of loss or disadvantage; as, to bargain away
      one's birthright. "The heir . . . had somehow bargained
      away the estate." --G. Eliot.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Bargain \Bar"gain\, n. [OE. bargayn, bargany, OF. bargaigne,
   bargagne, prob. from a supposed LL. barcaneum, fr. barca a
   boat which carries merchandise to the shore; hence, to
   traffic to and fro, to carry on commerce in general. See
   Bark a vessel. ]
   1. An agreement between parties concerning the sale of
      property; or a contract by which one party binds himself
      to transfer the right to some property for a
      consideration, and the other party binds himself to
      receive the property and pay the consideration.
      [1913 Webster]

            A contract is a bargain that is legally binding.
                                                  --Wharton.
      [1913 Webster]

   2. An agreement or stipulation; mutual pledge.
      [1913 Webster]

            And whon your honors mean to solemnize
            The bargain of your faith.            --Shak.
      [1913 Webster]

   3. A purchase; also ( when not qualified), a gainful
      transaction; an advantageous purchase; as, to buy a thing
      at a bargain.
      [1913 Webster]

   4. The thing stipulated or purchased; also, anything bought
      cheap.
      [1913 Webster]

            She was too fond of her most filthy bargain. --Shak.
      [1913 Webster]

   Bargain and sale (Law), a species of conveyance, by which
      the bargainor contracts to convey the lands to the
      bargainee, and becomes by such contract a trustee for and
      seized to the use of the bargainee. The statute then
      completes the purchase; i. e., the bargain vests the use,
      and the statute vests the possession. --Blackstone.

   Into the bargain, over and above what is stipulated;
      besides.

   To sell bargains, to make saucy (usually indelicate)
      repartees. [Obs.] --Swift.

   To strike a bargain, to reach or ratify an agreement. "A
      bargain was struck." --Macaulay.
      [1913 Webster]

   Syn: Contract; stipulation; purchase; engagement.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Bargain \Bar"gain\, v. i. [OE. barganien, OF. bargaigner, F.
   barguigner, to hesitate, fr. LL. barcaniare. See Bargain,
   n.]
   To make a bargain; to make a contract for the exchange of
   property or services; -- followed by with and for; as, to
   bargain with a farmer for a cow.
   [1913 Webster]

         So worthless peasants bargain for their wives. --Shak.
   [1913 Webster]

WordNet (r) 3.0 (2006):

bargain
    n 1: an agreement between parties (usually arrived at after
         discussion) fixing obligations of each; "he made a bargain
         with the devil"; "he rose to prominence through a series of
         shady deals" [syn: bargain, deal]
    2: an advantageous purchase; "she got a bargain at the auction";
       "the stock was a real buy at that price" [syn: bargain,
       buy, steal]
    v 1: negotiate the terms of an exchange; "We bargained for a
         beautiful rug in the bazaar" [syn: dicker, bargain]
    2: come to terms; arrive at an agreement

Moby Thesaurus II by Grady Ward, 1.0:

137 Moby Thesaurus words for "bargain":
   abatement of differences, accommodation, accord, act between,
   adjustment, advantageous purchase, advise with, agree, agree to,
   agreement, allow for, anticipate, arbitrate, arrange, arrangement,
   bargain for, barter, beat down, bid, bid for, binding agreement,
   blind bargain, bond, buy, call in, cartel, chaffer, cheapen,
   collective agreement, collogue, compact, compare notes,
   composition, compromise, concession, confer, confer with,
   consortium, consult, consult with, contract, convention, cop-out,
   counsel, count on, covenant, covenant of salt, deal, deliberate,
   desertion of principle, dicker, discuss, discuss with, do a deal,
   drive a bargain, employment contract, engage,
   evasion of responsibility, exchange, exchange observations,
   exchange views, expect, foresee, formal agreement, give-and-take,
   giveaway, giving way, go between, good buy, good deal,
   good pennyworth, haggle, hard bargain, have conversations, higgle,
   hold conference, horse trade, huckster, intercede, intermediate,
   interpose, intervene, ironclad agreement, jew down, judge,
   legal agreement, legal contract, make a deal, make terms, mediate,
   meet halfway, moderate, mutual agreement, mutual concession,
   negotiate, outbid, pact, paction, palaver, palter, parley,
   pennyworth, powwow, promise, protocol, put heads together,
   reason with, refer to, referee, represent, settlement,
   sit down together, sit down with, steal, step in, stipulate,
   stipulation, surrender, swap, take counsel, take into account,
   take up with, talk over, trade, trade-in, traffic, transaction,
   treat with, truck, umpire, underbid, understanding, undertake,
   union contract, valid contract, wage contract, yielding