English to English

noun (n)

• an advocate of nullification; someone who believes that a state can resist federal laws(noun.person)

  source: wordnet30
• an official who can invalidate or nullify(noun.person)

  Synonym:
  invalidator, voider
  

  source: wordnet30
• One who nullifies or makes void; one who maintains the right to nullify a contract by one of the parties.(noun)

  source: webster1913