imperturbability
noun
- the quality of being imperturbable; imperturbableness
Wiktionary
noun
Etymology: Etymology tree Proto-Indo-European *né Proto-Indo-European *n̥- Proto-Italic *n̥- Latin in-bor. Middle English in- English im- English perturbability English imperturbability From im- + perturbability.
- A state of calm, unruffled self-assurance; aplomb, composure.
“"As I sat alone at my breakfast--Mrs. Challenger is in the habit of keeping her room of a morning--it suddenly entered my head that it would be entertaining and instructive to see whether I could find any limits to this woman's imperturbability."”