Definition of: blackball

(blak′bôl′) v.t.
1. To use one's vote to ban from membership.
2. To exclude or ostracize: blackballed from the television industry.
—noun
1. A single negative vote resulting in the rejection of an application for membership.
2. Any willful exclusion or act of ostracism. [<BLACK + BALL¹ from the use of a black ball to signify a negative vote during balloting]
—black′·ball′er noun