zeal vs zealousness

zeal

noun
  • The fervour or tireless devotion for a person, cause, or ideal and determination in its furtherance; diligent enthusiasm; powerful interest. 

  • The collective noun for a group of zebras. 

zealousness

noun
  • The quality of being zealous; zeal. 

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