Source : Webster's Revised Unabridged Dictionary (1913)

Transaction \Trans*ac"tion\, n. [L. transactio, fr. transigere,
   transactum, to drive through, carry through, accomplish,
   transact; trans across, over + agere to drive; cf. F.
   transaction. See {Act}, {Agent}.]
   1. The doing or performing of any business; management of any
      affair; performance.

   2. That which is done; an affair; as, the transactions on the
      exchange.

   3. (Civil Law) An adjustment of a dispute between parties by
      mutual agreement.

   {Transaction of a society}, the published record of what it
      has done or accomplished.

   Syn: Proceeding; action; process.

   Usage: {Transaction}, {Proceeding}. A transaction is
          something already done and completed; a proceeding is
          either something which is now going on, or, if ended,
          is still contemplated with reference to its progress
          or successive stages.

   Note: `` We the word proceeding in application to an affray
         in the street, and the word transaction to some
         commercial negotiation that has been carried on between
         certain persons. The proceeding marks the manner of
         proceeding, as when we speak of the proceedings in a
         court of law. The transaction marks the business
         transacted; as, the transactions on the Exchange.''
         --Crabb.

Source : WordNet®

transaction
     n : the act of transacting within or between groups (as carrying
         on commercial activities); "no transactions are possible
         without him"; "he has always been honest is his dealings
         with me" [syn: {dealing}, {dealings}]

Source : Free On-Line Dictionary of Computing

transaction
     
        A unit of interaction with a {DBMS} or similar system.  It
        must be treated in a coherent and reliable way independent of
        other transactions.  See {atomic}.