World War I

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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. Abbreviation: WWI
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Also called Great War, War of the Nations.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2022


What was World War I?

World War I was a massive military conflict in Europe between 1914–18. Joining France and Great Britain, the U.S. fought on the Allied side against the German and Austria-Hungary empires.

It’s often noted for its military technology, such as tanks and mustard gas, which led to a death toll the world had never seen before, estimated at over 15 million.

How is World War I pronounced?

[ wurld wawr wuhn ]

What are some other words related to World War I?

  • WWI
  • First World War
  • The Great War

When was World War I?

Long-simmering tensions between European countries boiled over into World War I with the assassination of Austrian Archduke Franz Ferdinand in 1914 by a Serbian nationalist group known as the Black Hand. The event escalated into an all-out war between what came to be called the Central Powers (Austria-Hungary, Germany, Bulgaria, and the Ottoman Empire) and the Allies (Great Britain, France, Russia, Italy, Japan and later the United States). A previously isolationist United States joined the war in 1917, a hotly debated move that was motivated by the threat of German submarines to U.S. sea vessels.

World War I ended with the Treaty of Versailles in 1919 when the Central Powers officially surrendered to the Allies. The trauma of World War I would echo throughout Europe for decades after, however. In Germany alone, economic sanctions imposed by the Allied Powers led to crippling inflation and very low public morale, conditions that Adolf Hitler exploited—leading to World War II.

The term World War I was used as early as 1939 during the outbreak of World War II (a term which, interestingly, was used hypothetically as early as 1919). The phrase aimed to capture the extensive geopolitical reach of the war, fought by world powers on several continents and affecting economies across the globe.

World War I is notorious for the tremendous carnage and horrific destruction it wreaked in Europe. Trench warfare—which involved digging trenches near enemy lines and attempting to fire on or charge the other side—led to rampant disease, death and injury, and psychological damage in soldiers. Chemical warfare was also introduced, as both sides used agents such as mustard and chlorine gas to blind and debilitate enemy soldiers. The war also caused widespread famine and disease on the European continent off the battlegrounds.

World War I is also acknowledged as a major turning point in social and technological developments. With men fighting, an influx of women entered the workforce. As nationalism heightened, interest in intergovernmental organizations also grew and the US started emerging as a superpower. The introduction of tanks, battleships, military aircraft, machine guns, and other military technology changed the face of modern warfare.

How is World War I used in real life?

World War I inspired many works of art, including the books and films All Quiet on the Western Front and A Farewell to Arms, the film Lawrence of Arabia, the play War Horse, and paintings by John Nash.

Outside of its wide discussion in political and military history, World War I is popularly recognized by the images of trenches, its military technology, and haunting scenes of its violent aftermath.


More examples of World War I:

“In 1918, Hine was hired by the American Red Cross to document their work in Europe, as they provided aid to wounded soldiers and refugees affected by World War I.”

Alan Taylor, The Atlantic, May 2018


This content is not meant to be a formal definition of this term. Rather, it is an informal summary that seeks to provide supplemental information and context important to know or keep in mind about the term’s history, meaning, and usage.

How to use World War I in a sentence

British Dictionary definitions for World War I

World War I

the war (1914–18), fought mainly in Europe and the Middle East, in which the Allies (principally France, Russia, Britain, Italy after 1915, and the US after 1917) defeated the Central Powers (principally Germany, Austria-Hungary, and Turkey). The war was precipitated by the assassination of Austria's crown prince (Archduke Franz Ferdinand) at Sarajevo on June 28, 1914 and swiftly developed its major front in E France, where millions died in static trench warfare. After the October Revolution (1917) the Bolsheviks ended Russian participation in the war (Dec 15, 1917). The exhausted Central Powers agreed to an armistice on Nov 11, 1918 and quickly succumbed to internal revolution, before being forced to sign the Treaty of Versailles (June 28, 1919) and other treatiesAlso called: First World War, Great War
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Cultural definitions for World War I

World War I

A war fought from 1914 to 1918 between the Allies, notably Britain, France, Russia, and Italy (which entered in 1915), and the Central Powers: Germany, Austria-Hungary, Bulgaria, and the Ottoman Empire. The war was sparked by the assassination in 1914 of the heir to the throne of Austria (see Sarajevo) (see also Sarajevo). Prolonged stalemates, trench warfare, and immense casualties on both sides marked the fighting. The United States sought to remain neutral but was outraged by the sinking of the Lusitania by a German submarine in 1915 and by Germany's decision in 1916 to start unrestricted submarine warfare. In 1917, the United States entered the war on the side of the Allies and helped to tip the balance in their favor. In full retreat on its western front, Germany asked for an armistice, or truce, which was granted on November 11, 1918. By the terms of the Treaty of Versailles, signed in 1919, Germany had to make extensive concessions to the Allies and pay large penalties. The government leaders of World War I included Georges Clemenceau of France, David Lloyd George of Britain, Kaiser Wilhelm II of Germany, and Woodrow Wilson of the United States. World War I was known as the Great War, or the World War, until World War II broke out. (See map, next page.)

notes for World War I

German discontent over the terms of the Treaty of Versailles, and over the Weimar Republic that had accepted its provisions, led to the rise of the Nazis and Adolf Hitler, who pursued warlike policies not adequately opposed by the rest of Europe. Thus, barely twenty years after World War I was over, World War II began.

notes for World War I

A huge number of books, songs, and poems have been written about World War I. (See All Quiet on the Western Front; A Farewell to Arms; and “In Flanders Fields”.)

notes for World War I

Over There” was among the popular songs produced in the United States during the war.

notes for World War I

American foot soldiers in World War I were popularly called doughboys.

notes for World War I

November 11, the day the fighting ended, is observed in the United States as Veterans' Day.
The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.