adoption vs fosterage

adoption

noun
  • The state of being adopted; the acceptance of a child of other parents as if he or she were one's own child. 

  • An act of divine grace by which the redeemed in Christ are admitted to the privileges of the sons of God. 

  • Transfer between an old system to another (usually better) system. 

  • Ten consecutive wins against an opponent. 

  • The act of adopting. 

  • Admission to an institution, for example a hospital, clinic, mental asylum. 

  • The choosing and making that to be one's own which originally was not so; acceptance 

fosterage

noun
  • The act of fostering another's child as if it were one's own. 

  • The act of promoting or encouraging something. 

  • The act of caring for another human being or animal. 

  • The condition of being the foster child. 

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