puerile vs child

puerile is not a noun while child is a noun.

Word	Noun	Adjective	Verb	Adverb
puerile	No	Yes	No	No
child	Yes	No	No	No

puerile (noun)	child (noun)
	a young person of either sex
	a human offspring (son or daughter) of any age
	an immature childish person
	a member of a clan or tribe

puerile (adjective)	child (adjective)
of or characteristic of a child
displaying or suggesting a lack of maturity