imperturbable
1. [ adjective ] not easily perturbed or excited or upset; marked by extreme calm and composure
Synonyms: unflappable
Examples:

"hitherto imperturbable, he now showed signs of alarm" "an imperturbable self-possession" "unflappable in a crisis"

Related terms: composed
Similar spelling:   imperviable
  impermeable
  imperishable
  imperturbability
  impermeableness
  imperially
  Imperial_beard
  impermeability
  imperforate
  imperialism
  imperialist
  imperative
  impermanent
  imperial_decree
  impermanence
  impermanency
  imperatively
  imperialistic
  imperial_moth
  Imperial_gallon
  impermissible
  impertinent
  imperativeness
  import_barrier