backtracking vs reversal

backtracking

noun
  • The act of one who, or that which, backtracks; a retracing of one's steps. 

  • The usage of a runway as a taxiway, especially at private strips and smaller airports. 

  • The act of building all possible solutions to a problem incrementally, abandoning any candidate solution if it cannot lead to a valid solution. 

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 backtracking and reversal occurred in a corpus of books? (source: Google Ngram Viewer )