Merriam-Webster Collegiate Dictionary - naturalize

 verb  (-ized; -izing)  Date: 1559  transitive verb  1. to confer the rights of a national on; especially to admit to citizenship  2. to introduce into common use or into the vernacular  3. to bring into conformity with nature  4. to cause (as a plant) to become established as if native  intransitive verb to become established as if native  • naturalization noun