blacken vs blotch

blacken

verb
  • To cause to be or become black. 

  • 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. 

blotch

verb
  • To develop blotches, to become blotchy. 

  • To mark with blotches. 

noun
  • An irregularly shaped area. 

  • An uneven patch of color or discoloration. 

  • A bright or dark spot on old film caused by dirt and loss of the gelatin covering the film, due to age and poor film quality. 

  • A dark spot on the skin; a pustule. 

  • Blotting paper. 

  • Any of various crop diseases that cause the plant to form spots. 

  • Imperfection; blemish on one’s reputation, stain. 

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