pliant vs unflappable

pliant

adj
  • Easily influenced; tractable. 

  • Capable of plying or bending; readily yielding to force or pressure without breaking 

unflappable

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

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