noun (n)

• a slogan used to rally support for a cause(noun.communication)

  Example:
  Our watchword will be `democracy'.
  

  Synonym:
  battle cry, cry, rallying cry, war cry
  

  source: wordnet30
• a secret word or phrase known only to a restricted group(noun.communication)

  Synonym:
  countersign, parole, password, word
  

  source: wordnet30
• A word given to sentinels, and to such as have occasion to visit the guards, used as a signal by which a friend is known from an enemy, or a person who has a right to pass the watch from one who has not; a countersign; a password.(noun)

  source: webster1913