unflappable vs wavering

unflappable

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

wavering

adj
  • Being in doubt; indecisive. 

  • Fluctuating, uncertain, undetermined, unsteady. 

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