Monroe Doctrine: A policy that warned European powers to stay out of Latin American affairs. It reflected early American opposition to further colonization efforts by European countries.
Manifest Destiny: The belief that it was America's destiny and duty to expand its territory from coast to coast, justifying territorial acquisitions through war or negotiation.
Roosevelt Corollary: An addition made by President Theodore Roosevelt to the Monroe Doctrine, asserting America's right to intervene in Latin American countries if their internal affairs were deemed unstable or threatened American interests.