indispensability vs nonnegotiable

indispensability

noun

  • Something indispensable. 

  • The characteristic of being indispensable. 

nonnegotiable

noun

  • Something that is not negotiable. 

adj

  • Not negotiable; not subject to negotiation. 

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