per‧tur‧ba‧tion /ˌpɜːtəˈbeɪʃ
ən $ ˌpɜːrtər-/
noun1. [uncountable and countable] technical a small change in the movement, quality, or behaviour of something:
climatic perturbations2. [uncountable] formal worry about something that has happened or will happen
[TahlilGaran] Dictionary of Contemporary English ▲