impeachment The process by which formal charges of wrongdoing are brought against a president, a governor, or a federal judge. (pp. 514, 1011, 1053)

imperialism The system by which great powers gain control of overseas territories. The United States became an imperialist power by gaining control of Puerto Rico, Guam, the Philippines, and Cuba as a result of the Spanish-American War. (pp. 525, 537, 543, 544, 545, 667, 668, 669)

indentured servitude A system that committed poor immigrants to four to seven years of labor in exchange for passage to the colonies and food and shelter after they arrived. An indenture is a type of contract. (pp. 71, 73)

iron curtain A metaphor coined by Winston Churchill during his commencement address at Westminster College in Fulton, Missouri, in 1946, to refer to the political, ideological, and military barriers that separated Soviet-controlled Eastern Europe from the rest of Europe and the West following World War II. (pp. 866, 867, 868, 869)

isolationism A foreign policy perspective characterized by a desire to have the United States withdraw from the conflicts of the world and enjoy the protection of two vast oceans. (pp. 658, 753, 825, 826, 873)