A household in which an orphaned or delinquent child is placed (usually by a social-service agency)(noun)
WordNet. Princeton University. 2010.
Use "foster home" in a sentence
"After a brief stint in an orphanage, little Norma Jeane is bounced around from foster home to foster home."
"Not even a barren couple desperate for an adopted child wanted one with a cleft palate, so from the delivery room Gordie had become a dependent of the state, shuttled from one foster home to another until he was old enough to exit the system and try and fare on his own."