fosterage vs pupilage

fosterage

noun
  • The condition of being the foster child. 

  • 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. 

pupilage

noun
  • The condition of being a pupil. 

  • The period during which one is a pupil. 

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