fishtail vs undulate

fishtail

verb
  • To move with the tail swinging from side to side in this way. 

  • To swing the back of a vehicle (originally an aircraft) from side to side. 

  • To cause the back of (a vehicle) to swing from side to side. 

noun
  • The skidding of the back of a vehicle from side to side. 

  • A kind of chisel with a flared blade. 

  • The tail of a fish, or an object resembling this. 

undulate

verb
  • To move in wavelike motions. 

  • To cause to resemble a wave 

  • To appear wavelike. 

  • To cause to move in a wavelike motion. 

adj
  • Changing the pitch and volume of one's voice. 

  • Wavy in appearance or form. 

  • sinuous, winding up and down. 

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