inconstancy vs zeal

inconstancy

noun
  • Lack of constancy; lack of consistency in thought, emotion or action. 

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. 

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