Definition of "watchword"

"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."

1834, L[etitia] E[lizabeth] L[andon], chapter XXVII, in Francesca Carrara. […], volume I, London: Richard Bentley, […], (successor to Henry Colburn), page 321

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

1871, “Forward! Be Our Watchword”, Henry Alford (lyrics), Henry Thomas Smart (music)‎

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

1919, Boris Sidis, The Source and Aim of Human Progress‎

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.

1945 May, Harry S. Truman, Announcement of Germany's Surrender‎

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

1994, Tori Amos (lyrics and music), “Cornflake Girl”, in Under the Pink

The Esk Valley route to Whitby was a classic example: a basic four trains a day service has persisted for decades, with economy the watchword.

2019 October, James Abbott, “Esk Valley revival”, in Modern Railways, page 76

a Watchword sufficient for him that is wiſe

1625, George Sandys, Sacrae heptades