fosterling vs nestling

fosterling and nestling both are nouns.

Word	Noun	Adjective	Verb	Adverb
fosterling	Yes	No	No	No
nestling	Yes	No	No	No

As nouns, nestling is a hypernym of fosterling; that is, nestling is a word with a broader meaning than fosterling:

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

fosterling (noun)	nestling (noun)
a child who is raised by foster parents	young bird not yet fledged
	a young person of either sex