To naturalize means to officially grant citizenship to someone born in another country. When immigrants naturalize, they go through a formal legal process that makes them citizens of their new home. In the United States, people who naturalize take a citizenship test about American history and government, then take an oath of allegiance. After naturalizing, they receive the same rights and responsibilities as people born in the country, including the right to vote.

Many countries have naturalization processes, though the requirements vary. Some require living in the country for several years, learning the language, or passing tests about the nation's laws and values.

The word can also mean making something seem normal or natural in a new place. When a plant or animal naturalizes in a new environment, it adapts so well that it thrives there as if it had always belonged. Gardeners might talk about roses that have naturalized in their yard, meaning they come back year after year without special care. In this sense, naturalizing is about fitting in so completely that you become a permanent part of your new home.