backflip vs tumble

backflip

verb
  • To perform a backflip (rotation of body). 

  • To completely reverse a policy or opinion; perform a U-turn. 

noun
  • An act of rotating one's body 360 degrees in the backward direction. 

  • a total reversal in policy or opinion; a volte-face, a U-turn. 

tumble

verb
  • To perform gymnastics such as somersaults, rolls, and handsprings. 

  • To smoothe and polish, e.g., gemstones or pebbles, by means of a rotating tumbler. 

  • To muss, to make disorderly; to tousle or rumple. 

  • To obscure the audit trail of funds by means of a tumbler. 

  • To fall end over end; to roll over and over. 

  • To have sexual intercourse. 

  • To move or rush in a headlong or uncontrolled way. 

  • To drop rapidly. 

noun
  • A fall, especially end over end. 

  • An act of sexual intercourse. 

  • A disorderly heap. 

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