birr vs tremble

birr

verb
  • To lurch or set to spinning. 

  • To make a whirring noise; make a noise like that of revolving wheels, or of millstones at work. 

noun
  • The currency of Ethiopia, divided into 100 santims. 

  • A strong trilling. 

  • The force of movement; rush, impetus, momentum, driving force 

  • A whirring noise 

  • strength, vigor, energy 

tremble

verb
  • To shake, quiver, or vibrate. 

  • To fear; to be afraid. 

noun
  • A shake, quiver, or vibration. 

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