lexicow

perturb

/pərˈtɜːrb//pəˈtɜːb/·verb
A compass needle rests dead steady on north, the whole instrument at peace. Then a bar magnet slides in from the side and the needle is wrenched off true, swinging hard toward it. The magnet withdraws, and the needle is left to hunt its way back to north — overshooting, falling short, each swing smaller — until it settles again. One pass of that magnet was all it took to disturb a steady certainty and leave it searching for its bearing.
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Definition

To perturb something is to disturb it — to knock a settled system, orbit, or state of mind off its balance. From Latin perturbare, 'to throw into confusion', it is a favourite of science: a planet's path is perturbed by a passing mass, and a chemical equilibrium is perturbed by heat. Applied to people it is formal and usually negative — to be perturbed is to be unsettled or quietly worried, not merely surprised. The disturbance is often small, but it is enough to make a stable thing wobble.

Examples

  • A single careless remark was enough to perturb the otherwise serene meeting.
  • Add heat and you perturb the equilibrium, and the readings begin to fluctuate.
  • The astronomers watched the comet's orbit perturb slightly as it neared the planet.

Collocations

perturb the system·deeply perturbed·perturb the equilibrium·visibly perturbed

Synonyms

disturb·unsettle·disquiet·agitate·ruffle

Antonyms

calm·settle·reassure

Word family

perturbation (noun)·perturbed (adjective)

In TOEFL & IELTS

Useful in TOEFL science lectures (orbital and chemical 'perturbation') and in IELTS as a formal alternative to 'upset' or 'worry' ('investors were perturbed by the figures'). Stress falls on the second syllable, per-TURB, and the noun perturbation appears in academic reading far more often than the verb.