'Imperturbability' definitions:

Definition of 'imperturbability'

From: WordNet
noun
Calm and unruffled self-assurance; "he performed with all the coolness of a veteran" [syn: coolness, imperturbability, imperturbableness]

Definition of 'Imperturbability'

From: GCIDE
  • Imperturbability \Im`per*turb`a*bil"i*ty\, n. The state or quality of being imperturbable. [1913 Webster]