50 U.S.C. § 426(6) (2010) (Title 50—Chapter 15: National Security--Subchapter D: Protection of Certain National Security Information)
For the purposes of this title [50 U.S.C. §§ 421 et seq.]:
(6) The term "informant" means any individual who furnishes information to an intelligence agency in the course of a confidential relationship protecting the identity of such individual from public disclosure.