Alien
Statutory Law
8 U.S.C. § 1101(a)(3) (2010) (Title 8—Chapter 12: Immigration and Nationality)
(a) As used in this Act—
(3) The term "alien" means any person not a citizen or national of the United States.
Administrative Law
28 CFR § 21.1(b) [28 CFR PART 21—WITNESS FEES]
[…]
(b) Alien.
Any person who is not a citizen or national of the United States.