doubt vs fealty

doubt

verb
  • To be undecided about; to lack confidence in; to disbelieve, to question. 

noun
  • Disbelief or uncertainty (about something); (countable) a particular instance of such disbelief or uncertainty. 

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. 

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