Source : Webster's Revised Unabridged Dictionary (1913)

Conversation \Con`ver*sa"tion\, n. [OE. conversacio (in senses 1
   & 2), OF. conversacion, F. conversation, fr. L. conversatio
   frequent abode in a place, intercourse, LL. also, manner of
   life.]
   1. General course of conduct; behavior. [Archaic]

            Let your conversation be as it becometh the gospel.
                                                  --Philip. i.
                                                  27.

   2. Familiar intercourse; intimate fellowship or association;
      close acquaintance. ``Conversation with the best
      company.'' --Dryden.

            I set down, out of long experience in business and
            much conversation in books, what I thought pertinent
            to this business.                     --Bacon.

   3. Commerce; intercourse; traffic. [Obs.]

            All traffic and mutual conversation.  --Hakluyt.

   4. Colloquial discourse; oral interchange of sentiments and
      observations; informal dialogue.

            The influence exercised by his [Johnson's]
            conversation was altogether without a parallel.
                                                  --Macaulay.

   5. Sexual intercourse; as, criminal conversation.

   Syn: Intercourse; communion; commerce; familiarity;
        discourse; dialogue; colloquy; talk; chat.

   Usage: {Conversation}, {Talk}. There is a looser sense of
          these words, in which they are synonymous; there is a
          stricter sense, in which they differ. Talk is usually
          broken, familiar, and versatile. Conversation is more
          continuous and sustained, and turns ordinarily upon
          topics or higher interest. Children talk to their
          parents or to their companions; men converse together
          in mixed assemblies. Dr. Johnson once remarked, of an
          evening spent in society, that there had been a great
          deal of talk, but no conversation.

Source : WordNet®

conversation
     n : the use of speech for informal exchange of views or ideas or
         information etc.