For the purposes of this subchapter—
(4)
The terms “parent”, “father”, and “mother” mean a father, mother, father through adoption, mother through adoption, persons who have stood in loco parentis to a member of the military or naval forces at any time before entry into active service for a period of not less than one year, and a stepparent, if designated as beneficiary by the insured.
(Pub. L. 85–857, Sept. 2, 1958, 72 Stat. 1148, § 701; renumbered § 1901, Pub. L. 102–83, § 5(a), Aug. 6, 1991, 105 Stat. 406.)