child vs nipper

child and nipper both are nouns.

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

As nouns, child and nipper are synonyms defined as:

Other synonyms of child include fry, kid, minor, nestling, shaver, small fry, tiddler, tike, tyke, youngster.

child (noun)	nipper (noun)
a young person of either sex	a grasping structure on the limb of a crustacean or other arthropods
a human offspring (son or daughter) of any age	a young person of either sex
an immature childish person
a member of a clan or tribe