bagging vs undulation

bagging

noun
  • The act of putting anything into a bag. 

  • peak bagging 

  • bootstrap aggregating 

  • Cloth or other material for bags. 

  • Use of BVM to ventilate a patient. 

undulation

noun
  • An instance or act of undulating. 

  • A wavy appearance or outline; waviness. 

  • A wavelike curve; a smooth and regular rise and fall. 

  • A wavelike motion of the air; electromagnetic radiation. 

  • A tremulous tone produced by a peculiar pressure of the finger on a string. 

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