| Term | Definition |
| Francis Ferdinand | Archduke of Austria Hungary, who was assasinated. |
| Belligerent | pertaining to war or to those engaged in war |
| Trench Warfare | Fighting with trenches, mines, and barbed wire. Horrible living conditions, great slaughter, no gains, stalemate, used in WWI. |
| Austria- Hungary | the country where a revolution took place and decided to make a government of their own |
| Lusitania | American boat that was sunk by the German U-boats; made America consider entering WWI |
| War of Attrition | a type of war in which one side inflicts continous losses on the other in order to wear down its strengths |
| Triple Alliance | Germany, Italy, Autria-Hungary |
| Triple Entente | Russia, France, Great Britain |
| Alliance System | an association of groups, people, or nations who agree to cooperate to achieve a common goal |
| Mobilization | the gathering and transport of military troops and fighting equipment in preparation for war |
| Militarism | political orientation of a people or a government to maintain a strong military force |
| Nationalism | showing pride for ones country |
| Black Hand | the Serbian terrorist group that planned to assassinate Franz Ferdinand |
| Zimmerman Code | coded telegraph sent by Mexico that was intercepted by the British |
| Armistice | a state of peace agreed to between opponents so they can discuss peace terms |
| Bolsheviks | Led by Vladimir Lenin it was the Russian communist party that took over the Russian goverment during WWI |