appetite vs diffidence

appetite

noun
  • The desire for some personal gratification, either of the body or of the mind. 

  • Desire to eat food or consume drink. 

  • Any strong desire; an eagerness or longing. 

diffidence

noun
  • The state of being diffident, timid or shy; reticence or self-effacement. 

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