castaway vs flotsam

castaway

noun
  • A shipwrecked sailor. 

  • A discarded person or thing. 

  • An outcast; someone cast out of a group or society. 

adj
  • Cast adrift or ashore; marooned. 

  • Shipwrecked. 

  • Cast out; rejected or excluded from a group. 

flotsam

noun
  • Debris floating in a river or sea, in particular fragments from a shipwreck. 

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