baby of the family vs foster

baby of the family

noun
  • An adult member of an immediate family who is treated by others in the family, especially the parents, as though they were a child. 

  • The youngest member of an immediate family. 

  • A member of an immediate family who behaves as, or is treated as though they were the youngest member of a family. 

foster

noun
  • A foster parent. 

  • The care given to another; guardianship. 

verb
  • To cultivate and grow something. 

  • To nurture or bring up offspring, or to provide similar parental care to an unrelated child. 

  • To nurse or cherish something. 

adj
  • Related by such care. 

  • Receiving such care. 

  • Providing parental care to children not related to oneself. 

How often have the words baby of the family and foster occurred in a corpus of books? (source: Google Ngram Viewer )