Definition of imperturbability:

part of speech: noun

Self- possession; coolness.

Usage examples:

• Jack looked at him with amiable imperturbability William MacLeod Raine in "Brand Blotters".

• Since his wrestle with Cashel he had never quite recovered his former imperturbability in "".

• His imperturbability seemed to be leaving him. in "".

• During his absence, Heneage leaned back in his chair and relapsed into his usual imperturbability in "".