§ 5031.
For the purposes of this chapter, a “juvenile” is a person who has not attained his eighteenth birthday, or for the purpose of proceedings and disposition under this chapter for an alleged act of juvenile delinquency, a person who has not attained his twenty-first birthday, and “juvenile delinquency” is the violation of a law of the United States committed by a person prior to his eighteenth birthday which would have been a crime if committed by an adult or a violation by such a person of section 922(x).
([June 25, 1948, ch. 645], [62 Stat. 857]; [Pub. L. 93–415, title V, § 501], Sept. 7, 1974, [88 Stat. 1133]; [Pub. L. 103–322, title XI, § 110201(c)(1)], Sept. 13, 1994, [108 Stat. 2012].)