blacken vs mull

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. 

mull

verb
  • To powder; to pulverize. 

  • To chop marijuana so that it becomes a smokable form. 

  • To dull or stupefy. 

  • To heat and spice something, such as wine. 

  • To work (over) mentally; to cogitate; to ruminate. 

  • To join two or more individual windows at mullions. 

noun
  • An inferior kind of madder prepared from the smaller roots or the peelings and refuse of the larger. 

  • A stew of meat, broth, milk, butter, vegetables, and seasonings, thickened with soda crackers. 

  • dirt; rubbish 

  • A thin, soft muslin. 

  • A promontory. 

  • A snuffbox made of the small end of a horn. 

  • The gauze used in bookbinding to adhere a text block to a book's cover. 

  • Marijuana that has been chopped to prepare it for smoking. 

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