bairn vs nipper

bairn and nipper both are nouns.

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

As nouns, nipper is a hypernym of bairn; that is, nipper is a word with a broader meaning than bairn:

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

bairn (noun)	nipper (noun)
a child: son or daughter	a grasping structure on the limb of a crustacean or other arthropods
	a young person of either sex