disinterest vs halfheartedness

disinterest

noun
  • An absence of interest (attention or curiosity). 

  • The absence of interest (bias or stake). 

verb
  • To render disinterested. 

halfheartedness

noun
  • The characteristic of being halfhearted. 

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