There are several synonyms to describe a "bad child". One of the most commonly used terms is "naughty child". This implies that the child is mischievous or playful but has crossed the line. Other synonyms include "disobedient child", "unruly child" or "rebellious child". These phrases suggest that the child is not following instructions or is acting out of control. The terms "undisciplined child" or "spoiled child" suggest that the behavior is a result of a lack of discipline or overindulgence. Whatever term is used, it's important to remember that children's behavior should always be addressed in a loving and constructive manner.