perturbation

Everyday

1. (formal) Worry or anxiety; being upset: "She showed no perturbation." tree →
2. (science) A small change or disturbance in the movement or state of something, such as a planet's orbit being pulled by another planet. tree →

In the lessons

In science and astronomy, perturbations in Uranus's orbit led astronomers to discover Neptune in 1846. In maths and physics, a perturbation is a small push or change. In old-fashioned stories, it means worry.

Examples

• Small perturbations in Uranus's orbit helped find Neptune. tree →
• He listened without any sign of perturbation. tree →
• The spacecraft corrected for perturbations in its path. tree →
• A tiny perturbation can change the weather a lot. tree →
• Her perturbation grew as the dog did not come home. tree →
• Scientists measured the perturbation caused by the moon. tree →

Note

Formal. Verb: perturb (to worry); adjective: perturbed (worried), unperturbed (calm). In science it means a small disturbance, not a big crash.