enervation vs fervor

enervation

noun
  • State of being enervated; debility. 

  • Act of enervating; debilitation. 

fervor

noun
  • Heat. 

  • An intense, heated emotion; passion, ardor. 

  • A passionate enthusiasm for some cause. 

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