In Missouri as in all US states, child neglect is broadly defined.
Basically the law states, the custodian of a child (the adult caring for the child at the time of the accusation)is guilty of neglect if any of the following exist; the child does not have the proper food, clothing, shelter, medical treatment or supervision, and, (though the meaning is unclear), the adult caregiver failing to plan for the child's needs in the future.
Neglect can be anything from a child not having a proper diet, to truancy, to not having the immunizations required by law, and so on, and so on.
The interpretation of neglect laws are usually left to the investigating authority and/or the judge, based on the specific circumstances of the case in question.