per·​turb pər-ˈtərb How to pronounce perturb (audio)
perturbed; perturbing; perturbs

transitive verb

: to cause to be worried or upset : disquiet, unsettle
Half way down the next flight, she smiled to think that a char-woman's stare should so perturb her.Edith Wharton
The crowd didn't seem to perturb them in the slightest …Nick Hornby
: to throw into confusion : disorder
perturbing the social order
: to cause to experience a perturbation see perturbation sense 2
Newton finally realized that the planetary orbits would be only approximate ellipses, for the mutual attractions of the planets would perturb their paths.Owen Gingerich
perturbable adjective

Did you know?

With its per- prefix, perturb meant originally "thoroughly upset", though today the word has lost most of its intense edge. Perturb and perturbation are often used by scientists, usually when speaking of a change in their data indicating that something has affected some normal process. When someone is referred to as imperturbable, it means he or she manages to remain calm through the most trying experiences.

Choose the Right Synonym for perturb

discompose, disquiet, disturb, perturb, agitate, upset, fluster mean to destroy capacity for collected thought or decisive action.

discompose implies some degree of loss of self-control or self-confidence especially through emotional stress.

discomposed by the loss of his beloved wife

disquiet suggests loss of sense of security or peace of mind.

the disquieting news of factories closing

disturb implies interference with one's mental processes caused by worry, perplexity, or interruption.

the discrepancy in accounts disturbed me

perturb implies deep disturbance of mind and emotions.

perturbed by her husband's strange behavior

agitate suggests obvious external signs of nervous or emotional excitement.

in his agitated state we could see he was unable to work

upset implies the disturbance of normal or habitual functioning by disappointment, distress, or grief.

the family's constant bickering upsets the youngest child

fluster suggests bewildered agitation.

his declaration of love completely flustered her

Example Sentences

It perturbed him that his son was thinking about leaving school. the caller's strange remark perturbed me enough to keep me awake that night
Recent Examples on the Web The changing gravity could be substantial enough to perturb our comets. Sarah Scoles, Discover Magazine, 27 July 2016 None of this seemed to perturb the protesters, who’ve also targeted border crossings in Manitoba and Alberta, as well as Sarnia in Ontario. Washington Post, 10 Feb. 2022 Andrillon: These slow waves are thought to be associated with pauses in the activity of the individual neurons, which could perturb neural processes and lead to lapses of attention. Karen Hopkin, Scientific American, 15 Sep. 2021 The one-minute teaser opens on Sissy St. Claire holding forth on stage against a glittery fuchsia backdrop as increasingly sinister images flash and perturb the 1980s vibe. Anna Marie De La Fuente, Variety, 19 Jan. 2022 For example, manipulations that knock out a microRNA gene in MSCs might also disrupt the function of those stem cells and perturb their exosome output to an extent that far surpasses just the loss of that single microRNA as a cargo molecule. Michael Eisenstein, Scientific American, 17 June 2020 Upper-level winds are weak enough so as to not perturb Pamela’s growth, but there is no upper-level high-pressure ridge to enhance Pamela’s outflow. Washington Post, 12 Oct. 2021 Richard Frye, a pediatric neurologist and autism researcher at the Phoenix Children’s Hospital in Arizona, and his colleagues have found that such factors may also perturb the health of mitochondria in people with autism. Diana Kwon, Scientific American, 18 June 2021 The more opportunities there are to perturb the parameters of a design, the more potential there is to generate valuable perspective. James Scapa, Forbes, 28 May 2021 See More

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

Word History


Middle English, from Middle French perturber, from Latin perturbare to throw into confusion, from per- + turbare to disturb — more at turbid

First Known Use

14th century, in the meaning defined at sense 1

Time Traveler
The first known use of perturb was in the 14th century

Dictionary Entries Near perturb

Cite this Entry

“Perturb.” Dictionary, Merriam-Webster, Accessed 8 Feb. 2023.

Kids Definition


per·​turb pər-ˈtərb How to pronounce perturb (audio)
: to disturb greatly especially in mind
perturbable adjective

More from Merriam-Webster on perturb

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