Manifest destiny was a term coined during the 19th century to describe the belief that the expansion of the United States was not only inevitable but also necessary. While it is an iconic phrase that is still used today, there are many synonyms that can be used to describe this idea. These include the American destiny, territorial expansion, westward expansion, American imperialism, and territorialism. Each of these words conveys the same basic idea that the United States was destined to expand and control large portions of North America. Ultimately, these words all describe the belief that the United States was destined to become a great power, no matter the cost.