fathom vs mull

fathom

verb
  • Often followed by out: to deeply understand (someone or something); to get to the bottom of. 

  • To encircle (someone or something) with outstretched arms; specifically, to measure the circumference or (rare) length of something. 

  • To measure a depth; to sound. 

  • To conduct an examination or inquiry; to investigate. 

  • To measure the depth of (water); to take a sounding of; to sound. 

noun
  • Originally, the distance between an adult man's arms stretched out away from the sides of his torso so that they make a straight line perpendicular to his body, measured from the tips of the longest fingers of each hand, generally reckoned to be six feet (about 1.8 metres); subsequently used as a unit for water depth but now generally replaced by the metre. 

  • Depth of insight; mental reach or scope. 

  • An unspecified depth. 

mull

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

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

  • To dull or stupefy. 

  • To powder; to pulverize. 

  • To heat and spice something, such as wine. 

  • 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 fathom and mull occurred in a corpus of books? (source: Google Ngram Viewer )