For the purpose of this subchapter—
“agency” means—
(A) an Executive agency;
(B) the judicial branch;
(C) the Library of Congress;
(D) the Government Publishing Office; and
(E) the government of the District of Columbia;
(2) “employee” means an individual employed in or under an agency;
“head of each agency” means—
(A) the Director of the Administrative Office of the United States Courts with respect to the judicial branch; and
(B) the Mayor of the District of Columbia with respect to the government of the District of Columbia; and
(4) “United States”, when used in a geographical sense, means the several States and the District of Columbia.
(Pub. L. 89–554, Sept. 6, 1966, 80 Stat. 479; Pub. L. 90–623, § 1(10), Oct. 22, 1968, 82 Stat. 1312; Pub. L. 96–54, § 2(a)(31), Aug. 14, 1979, 93 Stat. 383; Pub. L. 113–235, div. H, title I, § 1301(b), Dec. 16, 2014, 128 Stat. 2537.)