frolic vs unhappiness

frolic

noun
  • Gaiety; merriment. 

  • A playful antic. 

verb
  • To make merry; to have fun; to romp; to behave playfully and uninhibitedly. 

unhappiness

noun
  • The feeling of not being happy 

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