The Collaborative International Dictionary of English v.0.48:

Bar \Bar\ (b[aum]r), v. t. [imp. & p. p. Barred (b[aum]rd); p.
   pr. & vb. n. Barring.] [ F. barrer. See Bar, n.]
   1. To fasten with a bar; as, to bar a door or gate.
      [1913 Webster]

   2. To restrict or confine, as if by a bar; to hinder; to
      obstruct; to prevent; to prohibit; as, to bar the entrance
      of evil; distance bars our intercourse; the statute bars
      my right; the right is barred by time; a release bars the
      plaintiff's recovery; -- sometimes with up.
      [1913 Webster]

            He barely looked the idea in the face, and hastened
            to bar it in its dungeon.             --Hawthorne.
      [1913 Webster]

   3. To except; to exclude by exception.
      [1913 Webster]

            Nay, but I bar to-night: you shall not gauge me
            By what we do to-night.               --Shak.
      [1913 Webster]

   4. To cross with one or more stripes or lines.
      [1913 Webster]

            For the sake of distinguishing the feet more
            clearly, I have barred them singly.   --Burney.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

barring \bar"ring\ n.
   the act of excluding someone by a negative vote or veto.

   Syn: blackball.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

barring
    n 1: the act of excluding someone by a negative vote or veto
         [syn: barring, blackball]