backtracking vs relocation

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. 

relocation

noun
  • The act of moving from one place to another. 

  • The assigning of addresses to variables either at linkage editing, or at runtime. 

  • Renewal of a lease. 

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