Sentence:  The day <WSD>armistice</WSD> was signed [chapter title] ... At five o'clock on the morning of 11 November 1918, a group of high-ranking German politicians and military officers entered a railway carriage in the Forest of Compiègne. They were met by delegates from the countries with which they had been at war. Three days earlier the French, British and Americans had prepared an "armistice" document which they demanded the Germans accept within three days. Inside the carriage the Germans signed the surrender document put before them. The document signalled that the war would stop in six hours' time, at the eleventh hour of the eleventh day of the eleventh month of 1918. 
Meaning of the word marked with <WSD> tags:  A formal agreement, especially between nations, to end combat.