Definitions for "Blackballing"
Blackballing was used in elections to membership of a Gentlemen's club (and similarly organised institutions, such as Freemasonry). The principle of such a club was that it was self-perpetuating: i.e. new members could only be elected by existing members. This was to ensure that new members were congenial to the old members, which helped to preserve the ethos (and exclusivity) of the club.