cop-out vs cover-up

cop-out

noun
  • An excuse made in order to avoid performing a task or duty; a reason offered when someone cops out. 

  • A person who cops out. 

  • Avoidance or inadequate performance of a task or duty; the action of copping out. 

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 cop-out and cover-up occurred in a corpus of books? (source: Google Ngram Viewer )