flexible vs persistent

flexible

noun
  • Something that is flexible. 

adj
  • Capable or being adapted or molded in some way. 

  • Capable of being flexed or bent without breaking; able to be turned or twisted without breaking. 

  • Willing or prone to give way to the influence of others; not invincibly rigid or obstinate. 

persistent

adj
  • Of data or a data structure: not transient or temporary, but remaining in existence after the termination of the program that creates it. 

  • Describing a fractal process that has a positive Brown function 

  • Lasting past maturity without falling off. 

  • non-transient. 

  • Obstinately refusing to give up or let go. 

  • Insistently repetitive. 

  • Indefinitely continuous. 

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