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adjective im·per·turb·able \ˌim-pər-ˈtər-bə-bəl\

Simple Definition of imperturbable

  • : very calm : very hard to disturb or upset

Source: Merriam-Webster's Learner's Dictionary

Full Definition of imperturbable

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

imperturbability play \-ˌtər-bə-ˈbi-lə-tē\ noun
imperturbably play \-ˈtər-bə-blē\ adverb

Examples of imperturbable in a sentence

  1. Although he seems outwardly imperturbable, he can get very angry at times.

  2. <the chef was absolutely imperturbable—even when the kitchen caught on fire>

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- and turbare, which means "to disturb." Other relatives of "imperturbable" include "disturb" and "turbid."

Origin of imperturbable

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

First Known Use: 15th century

Synonym Discussion of 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>.

IMPERTURBABLE Defined for Kids


adjective im·per·turb·able \ˌim-pər-ˈtər-bə-bəl\

Definition of imperturbable for Students

  1. :  hard to disturb or upset :  very calm <an imperturbable teacher>

Seen and Heard

What made you want to look up imperturbable? Please tell us where you read or heard it (including the quote, if possible).


to expose to danger or risk

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