im·​per·​turb·​able ˌim-pər-ˈtər-bə-bəl How to pronounce imperturbable (audio)
: marked by extreme calm, impassivity, and steadiness : serene
imperturbability noun
imperturbably adverb

Did you know?

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.

Choose the Right Synonym for imperturbable

cool, composed, collected, unruffled, imperturbable, nonchalant mean free from agitation or excitement.

cool may imply calmness, deliberateness, or dispassionateness.

kept a cool head

composed implies freedom from agitation as a result of self-discipline or a sedate disposition.

the composed pianist gave a flawless concert

collected implies a concentration of mind that eliminates distractions especially in moments of crisis.

the nurse stayed calm and collected

unruffled suggests apparent serenity and poise in the face of setbacks or in the midst of excitement.

harried but unruffled

imperturbable implies coolness or assurance even under severe provocation.

the speaker remained imperturbable despite the heckling

nonchalant stresses an easy coolness of manner or casualness that suggests indifference or unconcern.

a nonchalant driver

Examples of imperturbable in a Sentence

Although he seems outwardly imperturbable, he can get very angry at times. the chef was absolutely imperturbable—even when the kitchen caught on fire
Recent Examples on the Web Both were introverts by nature and, for the most part, imperturbable on the court. Cindy Shmerler, New York Times, 24 May 2024 Susie Glass, the crime boss Eddie reports to, is essentially a carbon copy of Michelle Dockery’s Rosalind, from her cherry-red lips to her sky-high stilettos to her generally imperturbable air. Angie Han, The Hollywood Reporter, 26 Feb. 2024 From lipomas and cysts to keloids and tumors, Lee tackles them all with professionalism and a seemingly imperturbable gag reflex. Briana Richert, James Mercadante,, 19 Feb. 2024 The effect of this combination, a mash-up of urgency and complacency — imperturbable emergency? — is dreamlike and a bit maddening, perhaps like Cassandra shouting her warning to the gullible Trojans. Philip Kennicott, Washington Post, 3 Nov. 2023 The Ioniq 6's solid structure is imperturbable, lending the car genuine composure over lumpy pavement on the most challenging sections of our test loop. Joe Lorio, Car and Driver, 28 June 2023 An imperturbable ANYmal is quietly conducting its inspection. IEEE Spectrum, 12 June 2019 Giugiaro's wedgy shape and wind-soothing particulars, unlike those of many aero cars, mesh with smooth and linear rack-and-pinion power steering to make the ES all but imperturbable in blustery winds. Larry Griffin, Car and Driver, 11 Apr. 2023 Huda knows that end is inevitable, and Awad is particularly superb — imperturbable, defiant, coolly magnetic — as a woman forced to define resistance on her own terms, who’s paid too dearly for her betrayals already to mind the final price that awaits. Los Angeles Times, 4 Mar. 2022

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'imperturbable.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


Middle English, from Late Latin imperturbabilis, from Latin in- + perturbare to perturb

First Known Use

15th century, in the meaning defined above

Time Traveler
The first known use of imperturbable was in the 15th century


Dictionary Entries Near imperturbable

Cite this Entry

“Imperturbable.” Dictionary, Merriam-Webster, Accessed 13 Jul. 2024.

Kids Definition


im·​per·​turb·​able ˌim-pər-ˈtər-bə-bəl How to pronounce imperturbable (audio)
: hard to disturb or upset
imperturbability noun
imperturbably adverb

More from Merriam-Webster on imperturbable

Last Updated: - Updated example sentences
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!