The story
From Zimmerwald + -ism, named after the Zimmerwald Conference, though they existed earlier as a cohesive group.
Etymology from Wiktionary, CC BY-SA 4.0.
Today it means: A set of anti-war political beliefs that emerged in 1915 in Siberia amongst political exiles in Irkutsk. Full definition →
From Zimmerwald + -ism, named after the Zimmerwald Conference, though they existed earlier as a cohesive group.
Etymology from Wiktionary, CC BY-SA 4.0.