castoff vs incredulity

castoff

noun
  • Something that has been rejected or discarded; a reject. 

adj
  • discarded, rejected. 

incredulity

noun
  • Unwillingness or inability to believe; doubt about the truth or verisimilitude of something; disbelief. 

  • Religious disbelief, lack of faith. 

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