castoff vs nugatory

castoff

adj
  • discarded, rejected. 

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

nugatory

adj
  • Ineffective, invalid or futile. 

  • Having no force, inoperative, ineffectual. 

  • Trivial, trifling or of little importance. 

  • Removable from a computer program with safety, but harmless if retained. 

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