castoff vs redundant

castoff

adj
  • discarded, rejected. 

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

redundant

adj
  • Dismissed from employment because no longer needed. 

  • Repetitive or needlessly wordy. 

  • Superfluous; exceeding what is necessary, no longer needed. 

  • Duplicating or able to duplicate the function of another component of a system, providing backup in the event the other component fails. 

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