boredom vs monotony

boredom

noun
  • An instance or period of being bored; A bored state. 

  • The state of being bored. 

monotony

noun
  • Tedium as a result of repetition or a lack of variety. 

  • The property of a monotonic function. 

  • The quality of having an unvarying tone or pitch. 

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