gumming vs mumbling

gumming

noun
  • The act of chewing without teeth. 

  • A disease marked by a discharge of gum, affecting stone fruit. 

  • The manual removal of clay, or "gum", from cut coal. 

  • The act of fastening with gum, especially the application of gum-water to a lithographic stone. 

mumbling

noun
  • An act in which someone mumbles something 

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