Wiktionary
foster family
n. A family having at least one foster child.
WordNet
foster family
n. the family of a fosterling
Usage examples of "foster family".
Banion had been placed in an orphanage by his mother when he was slightly over two years old, and had eventually been raised by a foster family that knew nothing of his royal ancestry.
Yeah, he'd call, and the whole foster family garbage would start again.