Delinquency is a minor crime, especially one committed by a youth. Cutting class all week to drive around town without your license is a sure sign of delinquency.
Delinquency can mean a particular violation, like stealing a car, but it may also refer to a more general trend of acting out and violating the law, like stealing cars daily and crashing them many times over. In this sense it’s often called juvenile delinquency. Another sense of delinquency is general neglect, particularly by someone who holds a formal position. The word can also refer to an unpaid debt. You’re thinking about those unpaid library fines now, right?