cud vs gnaw

cud

verb
  • To bring back into the mouth and chew a second time. 

noun
  • The portion of food which is brought back into the mouth by ruminating animals from their first stomach, to be chewed a second time. 

gnaw

verb
  • To bite something persistently, especially something tough. 

  • To produce excessive anxiety or worry. 

  • To corrode; to fret away; to waste. 

noun
  • the act of gnawing 

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