fad vs foible

fad

noun
  • A phenomenon that becomes popular for a very short time. 

foible

noun
  • A quirk, idiosyncrasy, or mannerism; an unusual habit that is slightly strange or silly. 

  • A weakness or failing of character. 

  • Part of a sword between the middle and the point, weaker than the forte. 

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