perturbation

American  

[pur-ter-bey-shuhn] / ˌpɜr tərˈbeɪ ʃən /

noun

1. the act of perturbing.

2. the state of being perturbed.

3. mental disquiet, disturbance, or agitation.

4. a cause of mental disquiet, disturbance, or agitation.

5. Astronomy. deviation of a celestial body from a regular orbit about its primary, caused by the presence of one or more other bodies that act upon the celestial body.

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perturbation British  

/ ˌpɜːtəˈbeɪʃən /

noun

1. the act of perturbing or the state of being perturbed

2. a cause of disturbance or upset

3. physics a secondary influence on a system that modifies simple behaviour, such as the effect of the other electrons on one electron in an atom

4. astronomy a small continuous deviation in the inclination and eccentricity of the orbit of a planet or comet, due to the attraction of neighbouring planets

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perturbation Scientific  

/ pûr′tər-bā′shən /

1. A small change in a physical system, most often in a physical system at equilibrium that is disturbed from the outside.

2. Variation in a designated orbit, as of a planet, that results from the influence of one or more external bodies. Gravitational attraction between planets can cause perturbations and cause a planet to deviate from its expected orbit. Perturbations in Neptune's orbit led to the discovery of the object—Pluto—that was causing the perturbation. Perturbations in the orbits of stars have led to the discovery of planetary systems outside of our Solar system.

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Other Word Forms

• perturbational
  adjective

Etymology

Origin of perturbation

1325–75; < Latin perturbātiōn- (stem of perturbātiō; see perturb, -ation); replacing Middle English perturbacioun < Anglo-French < Latin, as above

Explanation

When you're on an airplane with your friend who's terrified of flying, you'll be able to sense her perturbation, even if she doesn't say a word about how scared she is. The noun perturbation means "anxiety or uneasiness." Perturbation means "a state of agitation," or it can refer to whatever's causing the anxiety. Your brother's weird haircut could be the perturbation that's upsetting your mom at Thanksgiving dinner. It usually means a personal feeling of upset or nervousness, but perturbation can also be a physical disruption of some kind, like a perturbation in a river that makes the water become choppy and dangerous. In astronomy, perturbation is a change caused by the gravitational pull of a celestial body.

Example Sentences

But with 76 years of data to measure against, “we can provide the context needed to answer the question of, how big of a perturbation is this event?”

From Los Angeles Times • Jan. 29, 2025

But this roughness makes the surface mechanically unstable and susceptible to any small perturbation in temperature, pressure, or tiny defect.

From Science Daily • Oct. 4, 2023

Because the search space is vast and genetic experiments are costly, scientists often struggle to find the ideal perturbation for their particular application.

From Science Daily • Oct. 2, 2023

While there, he studied a key node of the mammalian immune system — dendritic cells — and their perturbation in HIV/AIDS.

From Los Angeles Times • Oct. 2, 2023

Tamika’s head lifted and our eyes met, her face a smashed-up combo of curiosity and perturbation.

From "Sir Fig Newton and the Science of Persistence" by Sonja Thomas