enervation vs feebleness

enervation

noun
  • State of being enervated; debility. 

  • Act of enervating; debilitation. 

feebleness

noun
  • The quality or state of being feeble; debility; infirmity. 

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