introvert vs invaginate

introvert

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

  • To think about internal or spiritual matters. 

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. 

invaginate

verb
  • To fold up or enclose into a sheath-like or pouch-like structure, either naturally or as part of a surgical procedure. 

  • To fold inward to create a hollow space where none had existed, as with a gastrula forming from a blastula. 

  • To turn or fold inwardly. 

adj
  • Having one portion of a hollow organ drawn back within another portion. 

  • sheathed 

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