instrumental vs must-have

instrumental

adj
  • essential or central; of great importance or relevance. 

  • Pertaining to, made by, or prepared for an instrument, especially a musical instrument (rather than the human voice). 

  • Applied to a case expressing means or agency, generally indicated in English by by or with with the objective. 

  • Serving as an instrument, medium, means, or agency. 

noun
  • The instrumental case. 

  • A composition written or performed without lyrics, sometimes using a lead instrument to replace vocals. 

must-have

adj
  • Essential to own. 

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

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