watch·word /-ˌwɝd/
  暗號,暗語,口令
  Watch·word n.
  1. 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.
  2. A sentiment or motto; esp., one used as a rallying cry or a signal for action.
     Nor deal in watchwords overmuch.   --Tennyson.
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  watchword
       n 1: a slogan used to rally support for a cause; "a cry to arms";
            "our watchword will be `democracy'" [syn: war cry, rallying
            cry, battle cry, cry]
       2: a secret word or phrase known only to a restricted group;
          "he forgot the password" [syn: password, word, parole,
           countersign]