back out vs pursue

back out

verb
  • To dare (someone) to not withdraw from a challenge. 

  • To withdraw from something one has agreed to do. 

  • To exit a mode or function. 

  • To draw from behind the back [+accusative = a knife etc.] (as also bare back). 

  • To undo (a change). 

  • Coordinate terms: cancel, call off, get cold feet 

  • To reverse (a vehicle) from a confined space. 

  • See also: sell short 

  • To bet on someone losing. 

  • Coordinate term: scare off 

pursue

verb
  • To follow urgently, originally with intent to capture or harm; to chase. 

  • To follow, travel down (a particular way, course of action etc.). 

  • To aim for, go after (a specified objective, situation etc.). 

  • To participate in (an activity, business etc.); to practise, follow (a profession). 

  • To act as a legal prosecutor. 

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