castoff vs superannuated

castoff

adj
  • discarded, rejected. 

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

superannuated

adj
  • Obsolete, antiquated. 

  • Retired or discarded due to age. 

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