|1.||a negative vote or veto|
|2.||a black wooden ball used to indicate disapproval or to veto in a vote|
|3.||(NZ) a hard boiled sweet with black-and-white stripes|
|4.||to vote against in a ballot|
|5.||to exclude (someone) from a group, profession, etc; ostracize|
|[C18: see sense 2]|
A rejection of an applicant's membership in a private organization, such as a club or fraternity. The term is derived from the traditional practice of members voting anonymously on admitting new members, using either a white marble (acceptance) or a black marble (denial). Acceptance must be unanimous; therefore, one black marble in the ballot box is enough to keep the applicant out of the organization.
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.