Communism: a system of government in which citizens share property and labor. Throughout history, the concept of communism has meant different things to different people. The ancient Greeks viewed it as an ideal vision for the future. Nineteenth-century workers hoped it would better their harsh lives. Idealists in the early twentieth century thought it would start a revolution that would change the world. It rose and fell in the twentieth-century in part because of economic pressure brought by the United States and because it became oppressive, with brutal dictators controlling the state.