fealty vs inconstancy

fealty

noun
  • Fidelity to one's lord or master; the feudal obligation by which the tenant or vassal was bound to be faithful to his lord. 

  • The oath by which this obligation was assumed. 

inconstancy

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

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