dispensable vs life-sustaining

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. 

life-sustaining

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