1. (Of the U.S. Senate) to reject a nominee, esp. for the U.S. Supreme Court, on grounds of the nominee’s unorthodox political and legal philosophy. • The term derives from the name of Robert Bork, President Ronald Reagan’s unsuccessful nominee for the Supreme Court in 1987.
2. (Of political and legal activists) to embark on a media campaign to pressure U.S. senators into rejecting a President’s nominee.
3. Generally, to smear a political opponent.