Source : Webster's Revised Unabridged Dictionary (1913)

Posting \Post"ing\, n.
   1. The act of traveling post.

   2. (Bookkeeping) The act of transferring an account, as from
      the journal to the ledger.

   {Posting house}, a post house.

Post \Post\, v. t. [imp. & p. p. {Posted}; p. pr. & vb. n.
   {Posting}.]
   1. To attach to a post, a wall, or other usual place of
      affixing public notices; to placard; as, to post a notice;
      to post playbills.

   Note: Formerly, a large post was erected before the sheriff's
         office, or in some public place, upon which legal
         notices were displayed. This way of advertisement has
         not entirely gone of use.

   2. To hold up to public blame or reproach; to advertise
      opprobriously; to denounce by public proclamation; as, to
      post one for cowardice.

            On pain of being posted to your sorrow Fail not, at
            four, to meet me.                     --Granville.

   3. To enter (a name) on a list, as for service, promotion, or
      the like.

   4. To assign to a station; to set; to place; as, to post a
      sentinel. ``It might be to obtain a ship for a lieutenant,
      . . . or to get him posted.'' --De Quincey.

   5. (Bookkeeping) To carry, as an account, from the journal to
      the ledger; as, to post an account; to transfer, as
      accounts, to the ledger.

            You have not posted your books these ten years.
                                                  --Arbuthnot.

   6. To place in the care of the post; to mail; as, to post a
      letter.

   7. To inform; to give the news to; to make (one) acquainted
      with the details of a subject; -- often with up.

            Thoroughly posted up in the politics and literature
            of the day.                           --Lond. Sat.
                                                  Rev.

   {To post off}, to put off; to delay. [Obs.] ``Why did I,
      venturously, post off so great a business?'' --Baxter.

   {To post over}, to hurry over. [Obs.] --Fuller.

Source : WordNet®

posting
     n 1: a sign posted in a public place as an advertisement; "a
          poster advertised the coming attractions" [syn: {poster},
           {placard}, {notice}, {bill}, {card}]
     2: (bookkeeping) a listing on the company's records; "the
        posting was made in the cash account"
     3: the transmission of a letter; "the postmark indicates the
        time of mailing" [syn: {mailing}]

Source : Free On-Line Dictionary of Computing

posting
     
        A message sent to a {newsgroup} or {mailing list} (may also be
        called "a post") or the act of sending it.  Distinguished from
        a "letter" or ordinary {electronic mail} message by the fact
        that it is broadcast rather than point-to-point.  It is not
        clear whether messages sent to a small mailing list are
        postings or e-mail; perhaps the best dividing line is that if
        you don't know the names of all the potential recipients, it
        is a posting.
     
        [{Jargon File}]