introvert vs wallflower

introvert

noun
  • 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. 

  • 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. 

  • A reserved person. 

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

  • To think about internal or spiritual matters. 

wallflower

noun
  • Any person who is socially awkward, shy, or reserved. 

  • A person who does not dance at a party, due to shyness or unpopularity; by extension, anyone who is left on the sidelines while an activity takes place. 

  • Any of several short-lived herbs or shrubs of the Erysimum genus with bright yellow to red flowers. 

  • Gastrolobium grandiflorum, a poisonous bushy shrub, endemic to Australia. 

verb
  • To stand shyly apart from a dance, waiting to be asked to join in. 

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