indispensability vs must-have

indispensability

noun

  • Something indispensable. 

  • The characteristic of being indispensable. 

must-have

noun

  • An item that one must own, or a feature that is essential to a service, etc. 

adj

  • Essential to own. 

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