Perturbation

Perturbation or perturb may refer to:
 * Perturbation theory, mathematical methods that give approximate solutions to problems that cannot be solved exactly
 * Perturbation (geology), changes in the nature of alluvial deposits over time
 * Perturbation (astronomy), alterations to an object's orbit (e.g., caused by gravitational interactions with other bodies)
 * Perturbation theory (quantum mechanics), a set of approximation schemes directly related to mathematical perturbation for describing a complicated quantum system in terms of a simpler one
 * Perturbation (biology), an alteration of the function of a biological system, induced by external or internal mechanisms
 * Perturbation function, mathematical function which relates the primal and dual problems