Source : Webster's Revised Unabridged Dictionary (1913)

Blackball \Black"ball`\, n.
   1. A composition for blacking shoes, boots, etc.; also, one
      for taking impressions of engraved work.

   2. A ball of black color, esp. one used as a negative in
      voting; -- in this sense usually two words.

Blackball \Black"ball`\, v. t. [imp. & p. p. {Blackballed}; p.
   pr. & vb. n. {Blackballing}.]
   1. To vote against, by putting a black ball into a ballot
      box; to reject or exclude, as by voting against with black
      balls; to ostracize.

            He was blackballed at two clubs in succession.
                                                  --Thackeray.

   2. To blacken (leather, shoes, etc.) with blacking.

Source : WordNet®

blackball
     n : the act of excluding someone by a negative vote or veto
         [syn: {barring}]
     v 1: expel from a community or group [syn: {banish}, {ban}, {ostracize},
           {ostracise}, {shun}, {cast out}]
     2: vote against; refuse to endorse; refuse to assent; "The
        President vetoed the bill" [syn: {veto}, {negative}]