dispensable vs extremely useful

dispensable

adj
  • Subject to dispensation; possible to relax, exempt from, or annul. 

  • Capable of being dispensed; distributable. 

  • Able to be done without; able to be expended; easily replaced. 

  • Not essential to be taken in as part of an organism's diet, as it can be synthesized de novo. 

extremely useful

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