Definition:
The "First World War," often abbreviated as WWI, refers to a major global conflict that took place from 1914 to 1918. It was fought between two main groups of countries: the Allies (which included nations like Russia, France, the British Empire, Italy, the United States, Japan, Romania, Serbia, Belgium, Greece, Portugal, and Montenegro) and the Central Powers (which included Germany, Austria-Hungary, Turkey, and Bulgaria).
While there aren't specific idioms or phrasal verbs directly related to "First World War," you might encounter phrases that reference the war in discussions about history, conflict, or alliances.
The "First World War" is a significant historical event that shaped many aspects of the modern world.