Naturalization is the official process that lets a person born in one country become a citizen of another country. You were not a citizen there from birth. You apply, you often wait a long time, you may take a test about the language and the laws, and if the government says yes, you become a citizen — usually with a new passport and many of the same rights as people born there (the exact rights depend on the country). This is a formal, legal word. In everyday talk people more often say become a citizen or get citizenship. You will meet naturalization on government forms, in the news, and in law. Though actually, the word can sound as if you slowly become natural in a new place, like learning the food and the jokes. That is not what it means here. Naturalization is a paper-and-law change: the country now counts you as a citizen. Do not mix it with nationalization, which is when a government takes over a private company — a completely different idea that only looks similar on the page.