Störterme

Störterme is a German term used in several disciplines to denote disturbance or perturbation terms that appear alongside the leading terms in a model, equation, or expression. The word combines Störung (disturbance) with Term(e) and is typically used descriptively rather than as a fixed mathematical category.

In mathematics and physics, Störterme are perturbation terms: small contributions that modify an exact or leading-order solution when a problem is only approximately solvable. They arise in perturbation theory, asymptotic expansions, and series solutions of differential equations. A common situation is a quantity written as a series x = x0 + εx1 + ε2x2 + ..., where ε is a small parameter; the terms εx1, ε2x2, and so on are Störterme. Analysts often assess these terms by their order in ε and may neglect higher-order Störterme to obtain practical approximations, or treat them systematically with perturbative methods.

In statistics and empirical modelling, the term can also refer, more loosely, to factors that disturb a model’s fit, such as measurement noise or neglected influences. This usage is less formal and varies by field.

The concept does not have a single formal definition and can be context-dependent. See also perturbation theory, perturbative expansion, asymptotic expansion, and error terms. If a different sense of Störterme is intended—such as a historical or literary usage—context is helpful, since the term’s standardized usage is limited.