Definition of "blackball"

(countable) A rejection; a vote against admitting someone.  examples

(countable) A black ball used to indicate such a negative vote.  examples

(countable) A kind of large black sweet.  examples

A substance for blacking shoes, boots, etc. or for taking impressions of engraved work.  examples

(uncountable) A game, a standardized version of the English version of eight-ball.  examples

(transitive) To vote against, especially in an exclusive organization.  quotations  examples

(transitive) To ostracize.  quotations  examples