blacken vs tarnish

blacken

verb
  • To make dirty. 

  • To defame or sully. 

  • To cook (meat or fish) by coating with pepper, etc., and quickly searing in a hot pan. 

  • To become black. 

  • To cause to be or become black. 

tarnish

verb
  • To compromise, damage, soil, or sully. 

  • To lose its lustre or attraction; to become dull. 

  • To oxidize or discolor due to oxidation. 

noun
  • Oxidation or discoloration, especially of a decorative metal exposed to air. 

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