imperturbation

[ im-per-ter-bey-shuh n ]
/ ˌɪm pər tərˈbeɪ ʃən /

noun

freedom from perturbation; tranquillity; calmness.

Origin of imperturbation

First recorded in 1640–50, imperturbation is from the Late Latin word imperturbātiōn- (stem of imperturbātiō). See im-2, perturbation