backflip vs reversal

backflip

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

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

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

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

reversal

noun
  • The state of being reversed. 

  • A change in fortune; a change from being successful to having problems. 

  • An instance of reversing. 

adj
  • Intended to reverse; implying reversal. 

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