D defs.my
Entry 3 senses Webster, 1913

Youthful

/yo͞oth'-fəl/ · Youth·ful · IPA /ˈjuːθfəl/
01 a. Not yet mature or aged; young.
  1. 1.
    Not yet mature or aged; young.
  2. 2.
    Of or pertaining to the early part of life; suitable to early life; as, youthful days; youthful sports.
  3. 3.
    Fresh; vigorous, as in youth.
    “After millions of millions of ages . . . still youthful and flourishing.” Bentley.
Syn. Puerile; juvenile.
-- Youthful, Puerile, Juvenile. Puerile is always used in a bad sense, or at least in the sense of what is suitable to a boy only; as, puerile objections, puerile amusements, etc. Juvenile is sometimes taken in a bad sense, as when speaking of youth in contrast with manhood; as, juvenile tricks; a juvenile performance. Youthful is commonly employed in a good sense; as, youthful aspirations; or at least by way of extenuating; as, youthful indiscretions. “Some men, imagining themselves possessed with a divine fury, often fall into toys and trifles, which are only puerilities.” Dryden. “Raw, juvenile writers imagine that, by pouring forth figures often, they render their compositions warm and animated.”