youthful \youth"ful\, a.
   1. not yet mature or aged; young. "two youthful knights."
      --dryden. also used figuratively. "the youthful season of
      the year." --shak.
      1913 webster

   2. of or pertaining to the early part of life; suitable to
      early life; as, youthful days; youthful sports. "warm,
      youthful blood." --shak. "youthful thoughts." --milton.
      1913 webster

   3. fresh; vigorous, as in youth.
      1913 webster

            after millions of millions of ages . . . still
            youthful and flourishing.             --bentley.
      1913 webster

   syn: puerile; juvenile.

   usage: 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." --blair.
          1913 webster -- youth"fully, adv. --
          youth"fulness, n.
          1913 webster
see also:
youthful puerile juvenile youth"fully youth"fulness 

youthfulness
     n : the freshness and vitality characteristic of a young person
         syn: youth, juvenility
see also:
youth juvenility