watchword

noun

1. A word used as a motto, as expressive of a principle, belief, or rule of action; a rallying cry.

   “"How this perpetual gaiety," exclaimed Louis, "jars upon the ear! Good Heaven! is farewell to be said so gladly? I sometimes start when I think upon the hollowness of all that surrounds me. I often wish my eye had the power of searching the inmost depths of the bosoms whose watchword is my name."”

   “For-ward! be our watchword, Steps and voices joined; / Seek the things before us, Not a look behind.”

   “Atrocities of the most vicious kind were justified by the watchwords: "This is war!" "Might is Right." "Necessity knows no law."”

   “We can repay the debt which we owe to our God, to our dead, and to our children only by work — by ceaseless devotion to the responsibilities which lie ahead of us. If I could give you a single watchword for the coming months, that word is: work, work, and more work.”

   “It's a peel out the watchword / Just peel out the watchword”

2. A prearranged reply to the challenge of a sentry or a guard; a password or signal by which friends can be known from enemies.

   “a Watchword sufficient for him that is wiſe”