castoff vs leftover

castoff

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

adj
  • discarded, rejected. 

leftover

noun
  • Something left behind; an excess or remainder. 

  • Remaining after a meal is complete or eaten for a later meal or snack. 

adj
  • Remaining; left behind; extra; in reserve. 

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