What term describes someone who is not a citizen or national of the United States?

The term that describes someone who is not a citizen or national of the United States is "alien." In immigration law, an alien is any individual who is not a U.S. citizen or national. This term encompasses a wide range of non-citizens, including lawful permanent residents, those holding temporary visas, and undocumented immigrants.

Using "alien" in this context is appropriate because it is a specific legal term that denotes the individual's status in relation to U.S. citizenship. While "foreigner" might seem like a synonym, it does not carry the same legal implications and can refer more broadly to anyone from another country, which might include citizens as well as non-citizens.

The choice "resident" refers to someone who resides in the U.S., which doesn't necessarily imply anything about their citizenship status. A "visa holder" specifically indicates a person who is in the country under a visa, yet they might still be classified as an alien if they are not U.S. citizens. Thus, the term "alien" most accurately captures the intended definition in the context of U.S. immigration law.