castoff vs cover-up

castoff

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

adj
  • discarded, rejected. 

cover-up

noun
  • An attempt to conceal or disguise something, especially a wrongdoing or a mistake. 

  • An item of clothing to be worn over a swimsuit while not in the water. 

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