imperturbable
Concise Oxford English Dictionary © 2008 Oxford University Press:
imperturbable /ˌɪmpəˈtəːbəb(ə)l/
▶adjective unable to be upset or excited.
– derivatives
imperturbability noun,
imperturbably adverb.
imperturbability noun,
imperturbably adverb.
'imperturbable' also found in these Oxford entries:

