For this definition we can go straight to the source - the IRS text:
Any financial account maintained by a foreign financial institution.
Other foreign financial assets, which include any of the following assets that are held for investment and not held in an account maintained by a financial institution.
Stock or securities issued by someone other than a U.S. person,
Any interest in a foreign entity, and
Any financial instrument or contract that has an issuer or counterparty that is other than a U.S. person.