bombinate vs whirr

bombinate

verb
  • to buzz or hum 

whirr

verb
  • To move or vibrate (something) with a buzzing sound. 

  • To make a sibilant buzzing or droning sound. 

  • To cause (something) to make such a sound. 

noun
  • A sibilant buzz or vibration; the sound of something in rapid motion. 

  • A bustle of noise and excitement. 

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