Definition of juvenile adjective from the Oxford Advanced American Dictionary

juvenile

adjective
/ˈdʒuvəˌnaɪl; ˈdʒuvənl/
 
 
1 [only before noun] (formal or law) connected with young people who are not yet adultsjuvenile crime/employmentjuvenile offenders2 (disapproving) silly and more typical of a child than an adult synonym childishjuvenile behaviorDon't be so juvenile!