fest vs festivity

fest

noun
  • A gathering for a specified reason or occasion. 

  • An event in which the act denoted by the previous noun occurs. 

festivity

noun
  • A festival or similar celebration. 

  • An experience or expression of celebratory feeling, merriment, gaiety. 

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