Word of the Day:

: marked by extreme calm, impassivity, and steadiness : serene

The imperturbable captain did not panic when the boat sailed into the path of a violent storm.

"Synchronicity is no stranger to sports. Back in 2016, a clip of two synchronized swimmers, strutting toward the pool like cool, imperturbable twins, went briefly viral." — Vinson Cunningham, The New Yorker, 17 January 2018

More example sentences

There is an interesting time lag between the appearance of imperturbable and its antonym, perturbable. Although imperturbable is known to have existed since the middle of the 15th century, perturbable didn't show up in written English until 1800. The verb perturb (meaning "to disquiet" or "to throw into confusion") predates both imperturbable and perturbable; it has been part of English since the 14th century. All three words derive from Latin perturbare (also meaning "to throw into confusion"), which in turn comes from the combination of per- (meaning "thoroughly") and turbare, which means "to disturb." Other relatives of imperturbable include disturb and turbid.