World War I

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A war fought from 1914 to 1918, in which Great Britain, France, Russia, Belgium, Italy, Japan, the United States, and other allies defeated Germany, Austria-Hungary, Turkey, and Bulgaria.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• proper noun The war from 1914 to 1918 between the Entente Powers of the British Empire, Russian Empire, France, Italy, the United States and other allied nations, against the Central Powers represented by Germany, Austria-Hungary, the Ottoman Empire, and Bulgaria.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• 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