foster child vs tike

foster child and tike both are nouns.

Word	Noun	Adjective	Verb	Adverb
foster child	Yes	No	No	No
tike	Yes	No	No	No

As nouns, tike is a hypernym of foster child; that is, tike is a word with a broader meaning than foster child:

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

foster child (noun)	tike (noun)
a child who is raised by foster parents	a young person of either sex
	a crude uncouth ill-bred person lacking culture or refinement