D defs.my
Entry 2 senses Webster, 1913

Under-age

/ŭn'-dẽr-āj'/ · Un·der-age · IPA /ˈʌndərˈeɪdʒ/
01 a. Not having arrived at adult age; hence, incapable legally of performing certain acts restricted to adults.
  1. 1.
    Not having arrived at adult age; hence, incapable legally of performing certain acts restricted to adults.
  2. 2.
    Not having arrived at adult age, or at years of discretion; hence, raw; green; immature; boyish; childish.[Obs.]
    “I myself have loved a lady, and pursued her with a great deal of under-age protestation.” J. Webster.