castoff vs threadbare

castoff

adj
  • discarded, rejected. 

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

threadbare

adj
  • banal or clichéd; trite or hackneyed 

  • shabby, frayed and worn to an extent that warp threads show 

  • damaged or shabby 

  • wearing clothes of threadbare material 

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