noun (n)

• someone who bolted from the Republican Party during the U.S. presidential election of 1884(noun.person)

  source: wordnet30
• a neutral or uncommitted person (especially in politics)(noun.person)

  Synonym:
  fencesitter, independent
  

  source: wordnet30
• A bolter from the Republican party in the national election of 1884; an Independent.(noun)

  source: webster1913