surf vs undulation

surf

noun
  • Waves that break on an ocean shoreline. 

  • A dance popular in the 1960s in which the movements of a surfboard rider are mimicked. 

  • The bottom of a drain. 

  • An instance or session of riding a surfboard in the surf. 

verb
  • To bodysurf; to swim in the surf at a beach. 

  • To surf at a specified place. 

  • To browse the Internet, television, etc. 

  • To ride a wave on a surfboard; to pursue or take part in the sport of surfing. 

undulation

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

  • An instance or act of undulating. 

  • A wavy appearance or outline; waviness. 

  • 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 surf and undulation occurred in a corpus of books? (source: Google Ngram Viewer )