lethargy vs zest

lethargy

noun
  • A condition characterized by extreme fatigue or drowsiness, deep unresponsiveness, or prolonged sleep patterns. 

  • A state of extreme torpor or apathy, especially with lack of emotion, energy or enthusiasm; (loosely) sluggishness, laziness. 

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 lethargy and zest occurred in a corpus of books? (source: Google Ngram Viewer )