imperturbable
adjective /ˌɪmpəˈtɜːbəbl/
/ˌɪmpərˈtɜːrbəbl/
(formal)- not easily upset or worried by a difficult situation; calm
- Above all he was imperturbable and never upset when things appeared to go against him.
- She faces challenges with imperturbable calm.
Word Originlate Middle English: from late Latin imperturbabilis, from in- ‘not’ + perturbare (from per- ‘completely’ + turbare ‘disturb’).