Definition of "foreign person"
from IRS form W-8BEN:
A foreign person includes a nonresident
alien individual, a foreign corporation, a foreign partnership,
a foreign trust, a foreign estate, and any other person that is
not a U.S. person. It also includes a foreign branch or office
of a U.S. financial institution or U.S. clearing organization if
the foreign branch is a qualified intermediary. Generally,
a payment to a U.S. branch of a foreign person is a payment to a
foreign person.
[IRS Form W-8BEN]
IRS Publication 519: Tax Guide for Aliens
IRS form W-8BEN