nonnegotiable vs requisite

nonnegotiable

noun

  • Something that is not negotiable. 

adj

  • Not negotiable; not subject to negotiation. 

requisite

noun

  • An indispensable item; a requirement. 

adj

  • Essential, indispensable, required. 

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