lifeblood vs zest

lifeblood

noun
  • Blood that is needed for continued life; blood regarded as the seat of life. 

  • That which is required for continued existence or function. 

zest

verb
  • To scrape the zest from a fruit. 

  • To make more zesty. 

noun
  • The outer skin of a citrus fruit, used as a flavouring or garnish. 

  • General vibrance of flavour. 

  • Enthusiasm; keen enjoyment; relish; gusto. 

  • The woody, thick skin enclosing the kernel of a walnut. 

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