| Term | Definition |
| Alliance | Formal agreement between two or more nations or powers to cooperate and come to one another's defense. |
| Allied Powers | World War I alliance of Britain, France and Russia; later joined by the United States and others. |
| Archduke Ferdinand | Heir to the Austrian throne, whose assassination in 1914 was the spark that started World War I. |
| Armistice | Mutual agreement to end fighting in a war. |
| Bolsheviks | 1917 Russian revolutionary group who seized power in Russia during the October Revolution and founded the Soviet Union. |
| Central Powers | World War I alliance of Germany, Austria-Hungary, and the Ottoman Empire (later joined by Bulgaria). |
| Collective | Large farm owned and operated by workers as a group. |
| Czar Nicholas II | The last absolute monarch of Russia who abdicated the throne and was murdered by communists. |
| 14 Points | A list of American President Woodrow Wilson's terms for guaranteeing peace and resolving future wars. |
| League of Nations | A group of more than 40 nations formed after World War I with the goal of settling problems through negotiation, not war. |
| Mandate | After World War I, a territory that was administered by a western power. |
| Militarism | Glorification of the military. |
| Neutrality | Policy of supporting neither side in a war. |
| No Man's Land | Empty land between opposing trench lines. |
| Pacifism | Opposition to all war. |
| "Powder Keg of Europe" | An area in Eastern Europe where any conflict may result in a war between several countries. |
| Propaganda | Spreading of ideas and information to promote a certain cause or to damage an opposing cause. |
| Rasputin | Russian peasant monk who was able to influence Russian politics by gaining the confidence of the Czarina. |
| Reparations | Payment for war damages or war damages caused by imprisonment. |
| Self-determination | Right of people to choose their own form of government. |
| Soviet | Council of workers and soldiers set up by Russian revolutionaries in 1917. |
| Stalemate | Deadlock in which neither side is able to defeat the other. |
| Total War | The channeling of a nation's entire resources into a war effort. |
| Treaty of Versailles | The treaty that ended World War I, which blamed Germany for causing the war. |
| Trench Warfare | Type of warfare where troops dig into the land and fight. |
| Vladimir Lenin | First Communist leader of Russia, who promised "peace, bread and land". |