foster parent vs foster-parent

foster parent and foster-parent both are nouns.

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

As nouns, foster parent and foster-parent are synonyms defined as:

foster parent and 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

foster parent (noun)	foster-parent (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 acts as parent and guardian for a child in place of the child's natural parents but without legally adopting the child