Why was "tantrum" trending last week?
1707, from French armistice (1680s), coined on the model of Latin solstitium (see solstice), etc., from Latin arma "arms" (see arm (n.2)) + -stitium (used only in compounds), from sistere "cause to stand" (see assist).
The word is attested in English from 1660s in the Latin form armistitium. German Waffenstillstand is a loan-translation from French. Armistice Day (1919) marked the end of the Great War of 1914-18 on Nov. 11, 1918. In Britain, after World War II, it merged with Remembrance Day. In U.S., Armistice Day became a national holiday in 1926. In 1954, to honor World War II and Korean War veterans as well, it was re-dubbed Veterans Day.