1. 
2. 
[syn: adolescent, jejune, juvenile, puerile]
The Collaborative International Dictionary of English v.0.48:
Puerile \Pu"er*ile\, a. [L. puerilis, fr. puer a child, a boy:
   cf. F. pu['e]ril.]
   Boyish; childish; trifling; silly.
   [1913 Webster]
         The French have been notorious through generations for
         their puerile affectation of Roman forms, models, and
         historic precedents.                     --De Quincey.
   [1913 Webster]
   Syn: Youthful; boyish; juvenile; childish; trifling; weak.
        See Youthful.
        [1913 Webster]
WordNet (r) 3.0 (2006):
puerile
    adj 1: of or characteristic of a child; "puerile breathing"
    2: displaying or suggesting a lack of maturity; "adolescent
       insecurity"; "jejune responses to our problems"; "their
       behavior was juvenile"; "puerile jokes" [syn: adolescent,
       jejune, juvenile, puerile]
Moby Thesaurus II by Grady Ward, 1.0:
31 Moby Thesaurus words for "puerile":
   asinine, babish, babyish, beardless, boyish, boylike, calflike,
   childish, childlike, coltish, foolish, girlish, girllike, immature,
   inconsequential, infantile, infantine, insignificant,
   irresponsible, juvenile, kiddish, maiden, maidenly, puplike,
   puppyish, puppylike, ridiculous, shallow, silly, sophomoric,
   trivial