Well, this is a bit tricky (kinda) but I'll answer it to the best of my ability. Do you know how people often refer to U.S. and North Korean tensions rising as resulting in "World War 3"? That's what it was with WW2. the term "World War II” dates as far back as February of 1919 when it was used in a Manchester Guardian article. Franklin D. Roosevelt was the first to coin the term in actual wartime in 1941. Many Americans followed in Roosevelt's footsteps with that one. In Britain, the Second World War was simply titled "The War" until the late 40s. Although Roosevelt popularized the term, he wanted a new name for it. In 1942, he asked the public to think of more names for the war. In the next few weeks, the War Department would receive over 15,000 public submissions with names like "The War Against Enslavement" and "The War for Civilization". Roosevelt had another choice, "The Survival War", but none of these had the power to stay. It was decided to be called "the Second World War" or "WWII" and the title "WWI" and "First World War" was given to the Great War.