1. A child who comes home from school in the absence of his/her parents. A child who is not ready to be a latch key kid should be sent either to daycare or a friend's house in the afternoon.
2. Could also mean a young/apprentice locksmith.
1. Jimmy was a latch-key kid because his mom works afternoons and his dad is in jail for burglary and arson. Maybe he shouldn't have been going home alone because he's been missing since last thursday. Probably got lost, the dumb little bastard.
2. Jimmy, our latch-key kid, got electrocuted while trying to unlock an outlet cover.