foster-parent vs defender

foster-parent and defender both are nouns.

Word	Noun	Adjective	Verb	Adverb
foster-parent	Yes	No	No	No
defender	Yes	No	No	No

As nouns, defender is a hypernym of foster-parent; that is, defender is a word with a broader meaning than foster-parent:

foster-parent: a person who acts as parent and guardian for a child in place of the child's natural parents but without legally adopting the child
defender: a person who cares for persons or property

Other hypernyms of foster-parent include guardian, protector, shielder.

foster-parent (noun)	defender (noun)
a person who acts as parent and guardian for a child in place of the child's natural parents but without legally adopting the child	a person who cares for persons or property
	a fighter who holds out against attack