The Collaborative International Dictionary of English v.0.48:

juvenile delinquent \ju"ve*nile de*lin"quent\, n.
   A child or person of minor age who commits acts which would
   be considered criminal if performed by an adult, such as
   theft, vandalism, or violence; especially, one who habitually
   acts in such an antisocial manner and cannot be controlled by
   parents. Abbreviated JD.
   [PJC]

WordNet (r) 3.0 (2006):

juvenile delinquent
    n 1: a young offender [syn: delinquent, juvenile delinquent]