on the run vs untraceable

on the run

prep
  • At a disadvantage; forced to abandon a position. 

  • Constantly traveling or moving from place to place. 

  • Used other than figuratively or idiomatically: see on, run. 

  • Fleeing. 

untraceable

adj
  • Not able to be traced or tracked down 

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