unflappable[adjective]Synonyms: imperturbable, calm, collected, composed, cool, impassive, level-headed, self-possessed
Related Words: easy,
relaxed [TahlilGaran] English Synonym Dictionary ▲
un‧flap‧pa‧ble /ʌnˈflæpəb
əl/
adjective informal having the ability to stay calm and not become upset, even in difficult situations
[TahlilGaran] Dictionary of Contemporary English ▲