introvert vs mousekin

introvert

noun
  • An organ or other body part that is or can be turned inside out, especially an anterior portion of some annelid worms capable of retraction. 

  • An introverted person: one who is considered more thoughtful than social, with a personality more inwardly than outwardly directed; one who often prefers to have time in non-social situations. 

  • A reserved person. 

verb
  • To withdraw an organ or body part within itself or its base. 

  • To think about internal or spiritual matters. 

mousekin

noun
  • A little mouse. 

  • A baby mouse. 

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