bumble vs stammer

bumble

verb
  • To act in an inept, clumsy or inexpert manner; to make mistakes. 

  • To boom, as a Eurasian bittern. 

  • To buzz, as a fly. 

noun
  • A bumble-bee. 

  • A confusion; a jumble. 

  • The Eurasian bittern. 

stammer

verb
  • To utter with a stammer, or with timid hesitancy. 

  • To keep repeating a particular sound involuntarily during speech. 

noun
  • A speech defect whereby someone speaks with a stammer 

  • The involuntary repetition of a sound in speech. 

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