flexible vs unflappable

flexible

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

  • 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. 

noun
  • Something that is flexible. 

unflappable

adj
  • Remaining composed and level-headed at all times; impossible to fluster; not becoming frustrated or irritated easily. 

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