What does "blackball" mean?

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

Additional senses

  1. 2.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. 3.To blacken (leather, shoes, etc.) with blacking.

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