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]