naturalize
verb [ I or T ]
LAW ( UK also naturalise) uk/ˈnætʃərəlaɪz/ usto make someone a citizen of a country they were not born in, or to become a citizen of a country you were not born in:
be/become naturalized About 700,000 immigrants were naturalized as citizens last year, officials said.
Not all permanent residents are eligible to naturalize.
a naturalized citizen