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

Example Sentences

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 Cleopatra’s death, by contrast, unfolds in an atmosphere of imperturbable serenity, implicitly defying Caesar’s cold new order. Alex Ross, The New Yorker, 26 Sep. 2022 Smock, a preacher who went by the name Brother Jed, was imperturbable. Susan Orlean, The New Yorker, 13 Sep. 2022 That is especially true for Michaels, who is famously imperturbable under pressure, professorially philosophical about the businesses of comedy and television, and consistently medium-cool in his overall demeanor. Bill Carter For Cnn Business Perspectives, CNN, 9 Sep. 2022 Gerald Kyd also shines as all-seeing, imperturbable Dr. Dorn, whether wearyingly suggesting Arkadina’s ailing brother simply needs to take Paracetamol or thoughtfully dispensing kindness. David Benedict, Variety, 8 July 2022 Inquisitive and imperturbable, Nelly is our guide through the story, which somehow unfolds on her initiative. Anthony Lane, The New Yorker, 21 Apr. 2022 The fat man was still sitting with the same imperturbable calm. Vladimir Sorokin, The New Yorker, 27 Sep. 2021 And the flexibility of the imperturbable Audi mill allows a fifth-gear drive from near idle to redline, a trait reminiscent of the early Lamborghini GTs and one which makes the Spyker a pussycat to drive around town. Robert Ross, Robb Report, 20 Sep. 2021 The Emmy winner stars as Del Harris, the imperturbable police chief in the languishing Rust Belt town of Buell, Pennsylvania. Ew Staff,, 10 Sep. 2021 See More

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'imperturbable.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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 27 Nov. 2022.

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!

Odd Habits and Quirks

  • image1926873504
  • Which of the following best describes an easily irritated person?
Spell It

Hear a word and type it out. How many can you get right?

Universal Daily Crossword

A daily challenge for crossword fanatics.