phlegmatic vs unflappable

phlegmatic

adj
  • Not easily excited to action or passion; calm; sluggish. 

  • Generating, causing, or full of phlegm. 

noun
  • One who has a phlegmatic disposition. 

unflappable

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

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