incapable of being disturbed or troubled
Ancient stories tell of sages who were so imperturbable that they could not be distracted from meditation even by violent physical attacks on them.
in (in), per (thoroughly)#turba (turmoil) (Latin)
dispassionate, impassive, imperturbable, stoic, stolid
Imperturbable: im + pertur (like tur tur) + babble (just talking foolishly. So, the person who never do any tur-tur and never babbles is a very cool, calm and peaceful guy. im-'not'+perturb (able), meaning not perturbed. so a person who is not perturbed stays calm and placid. Imperturbable- im+perturbable. Perturb rhymes with with Disturb. Imperturbable is a person whom you cannot disturb/upset easily - that's why he is always calm.