latchkey child: a school-age child who is home without adult supervision for part of the day (especially after school until a parent returns home from work)
entity: that which is perceived or known or inferred to have its own distinct existence (living or nonliving)
phenylketonuria: a genetic disorder of metabolism; lack of the enzyme needed to turn phenylalanine into tyrosine results in an accumulation of phenylalanine in the body fluids which causes various degrees of mental deficiency