Nouns:
* Childhood: The period of time between birth and adulthood.
* Childless: Having no children.
* Childbirth: The process of giving birth to a child.
* Childcare: The care and supervision of children.
* Childproof: Designed to prevent children from accessing or being harmed by something.
Verbs:
* Childproof: To make something safe for children.
* Childbear: To give birth to a child.
Adjectives:
* Childish: Behaving in a way that is typical of a child.
* Childlike: Having the innocence and simplicity of a child.
Other:
* Child-rearing: The process of raising children.
* Child-friendly: Suitable for children.
* Child-centered: Focused on the needs and interests of children.
These are just a few examples. There are many more words that use "child" as a root word, depending on the specific context and meaning you're looking for.