blackball

Short definition from Wiktionary

Noun

1. 1
   A rejection; a vote against admitting someone.
2. 2
   A black ball used to indicate such a negative vote.
3. 3
   A kind of large black sweet, a black-colored gobstopper.
4. 4
   A substance for blacking shoes, boots, etc. or for taking impressions of engraved work.
5. 5
   A game, a standardized version of the English version of eight-ball.

Verb

1. 1
   To vote against, especially in an exclusive organization.
2. 2
   To ostracize.

Proper noun

1. 1
   A small town in Grey district, West Coast, New Zealand, with a history of gold and coal mining.