inanity vs thoughtlessness

inanity

noun
  • The property of being inane, of lacking material of interest or satisfaction, emptiness. 

  • Something that is inane. 

thoughtlessness

noun
  • heedless disregard for the consequences of one's actions 

  • disregard for other's feelings 

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