1. Not easily upset, confused, or disconcerted; remaining calm and composed in difficult situations
She remained unflappable despite the chaos around her.
Ela permaneceu imperturbável apesar do caos ao seu redor.
2. Characterized by coolness and equanimity under pressure
The pilot's unflappable demeanor reassured the passengers during turbulence.
A atitude imperturbável do piloto tranquilizou os passageiros durante a turbulência.