Akademik

World War I
noun
a war between the allies (Russia, France, British Empire, Italy, United States, Japan, Rumania, Serbia, Belgium, Greece, Portugal, Montenegro) and the Central Powers (Germany, Austria-Hungary, Turkey, Bulgaria) from 1914 to 1918 (Freq. 2)
Syn: ↑World War 1, ↑Great War, ↑First World War, ↑War to End War
Instance Hypernyms: ↑world war
Part Meronyms:
Battle of the Marne, ↑Belleau Wood, ↑Chateau-Thierry, ↑Marne River, ↑Caporetto, ↑battle of Caporetto, ↑Dardanelles, ↑Dardanelles campaign, ↑Jutland, ↑battle of Jutland, ↑Meuse, ↑Meuse River, ↑Argonne, ↑Argonne Forest, ↑Meuse-Argonne, ↑Meuse-Argonne operation, ↑Soissons, ↑battle of Soissons-Reims, ↑battle of the Chemin-des-Dames, ↑battle of the Aisne, ↑Somme, ↑Somme River, ↑Battle of the Somme, ↑Tannenberg, ↑battle of Tannenberg, ↑Verdun, ↑battle of Verdun, ↑Ypres, ↑battle of Ypres, ↑first battle of Ypres, ↑second battle of Ypres, ↑third battle of Ypres

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the war fought mainly in Europe and the Middle East, between the Central Powers and the Allies, beginning on July 28, 1914, and ending on November 11, 1918, with the collapse of the Central Powers. Abbr.: WWI Also called Great War, War of the Nations.

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World War I UK [ˌwɜː(r)ld wɔː(r) ˈwʌn] US [ˌwɜrld wɔr ˈwʌn] mainly american
the first world war http://www.macmillandictionary.com/med2cd/weblinks/world-war-i.htm
Thesaurus: cold war and wars in historyhyponym

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a war (1914 - 18) in which the Central Powers (Germany and Austria - Hungary, joined later by Turkey and Bulgaria) were defeated by an alliance of Britain and its dominions, France, Russia, and others, joined later by Italy and the U.S
Encyclopedic information:
Political tensions over the rise of the German Empire were the war's principal cause, although it was set off by the assassination of Archduke Franz Ferdinand of Austria by a Bosnian Serb nationalist in Sarajevo, an event used as a pretext by Austria for declaring war on Serbia. Most of the fighting took place on land in Europe and was generally characterized by long periods of bloody stalemate; the balance eventually shifted in the Allies' favor in 1917 when the U.S. joined the war. Total casualties of the war are estimated at 10 million killed. One of the consequences of the war was the collapse of the German, Austro-Hungarian, Russian, and Ottoman empires

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ˌWorld ˌWar ˈOne 7 [World War One] (also ˌWorld ˌWar ˈI) noun
= First World War

Useful english dictionary. 2012.