The Collaborative International Dictionary of English v.0.48:

Juvenility \Ju`ve*nil"i*ty\, n.; pl. Juvenilities. [L.
   juvenilitas: cf. F. juv['e]nilit['e].]
   [1913 Webster]
   1. Youthfulness; adolescence. --Glanvill.
      [1913 Webster]

   2. The manners or character of youth; immaturity. --Glanvill.
      [1913 Webster]

WordNet (r) 3.0 (2006):

juvenility
    n 1: lacking and evidencing lack of experience of life [syn:
         callowness, jejuneness, juvenility]
    2: the freshness and vitality characteristic of a young person
       [syn: youth, youthfulness, juvenility]

Moby Thesaurus II by Grady Ward, 1.0:

29 Moby Thesaurus words for "juvenility":
   adolescence, bloom, budtime, early years, florescence,
   flowering time, greenness, jeunesse, juvenescence,
   my burning youth, my green age, prime of life, puberty, pubescence,
   salad days, seedtime of life, spring, springtide, springtime,
   springtime of life, tender age, tenderness, young blood, youngness,
   youth, youthfulness, youthhead, youthhood, youthiness