Blackball

to vote against (a candidate, applicant, etc.).
to exclude socially; ostracize:
The whole town blackballed them.
to reject (a candidate) by placing a blackball in the ballot box.
a negative vote, especially in deciding on an applicant or candidate.
a black ball placed in a ballot box signifying a negative vote.
Contemporary Examples

Do Banks Still Play Us for Fools? Charlie Gasparino September 12, 2010
Karl Rove’s Flameout Matt Latimer October 21, 2010

Historical Examples

Deering of Deal Latta Griswold
Sparkling Gems of Race Knowledge Worth Reading Various
The Newcomes William Makepeace Thackeray
Tristram of Blent Anthony Hope
The Book of Snobs William Makepeace Thackeray
Letters of a Dakota Divorcee Jane Burr
The Sportswoman’s Library, Vol. 1 of 2 Various
The Vice Bondage of a Great City or the Wickedest City in the World Robert O. Harland

noun
a negative vote or veto
a black wooden ball used to indicate disapproval or to veto in a vote
(NZ) a hard boiled sweet with black-and-white stripes
verb (transitive)
to vote against in a ballot
to exclude (someone) from a group, profession, etc; ostracize
v.

Note: The term is now applied generally to efforts — especially unreasonable or vengeful actions — to keep a people or groups out of organizations they wish to join.