dross vs flotsam

dross

noun
  • A waste product from working with metal. 

  • Worthless or trivial matter. 

  • The impurities in metal. 

  • Waste or impure matter. 

  • Residue that forms on the surface of molten metal from oxidation. 

verb
  • To remove dross from. 

flotsam

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

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