imperturbable

Từ điển WordNet v3.1 - WordNet Dictionary

adjective

not easily perturbed or excited or upset;
marked by extreme calm and composure
- hitherto imperturbable, he now showed signs of alarm
- an imperturbable self-possession
- unflappable in a crisis
• Syn:
unflappable
• Similar to:
composed
• Derivationally related forms:
imperturbableness, imperturbability