reagieren

Reagieren is a German verb meaning to react or respond, in everyday usage and in scientific contexts alike. It can refer to a person's emotional or behavioral response to a stimulus, a reply to a statement, or a chemical or physiological change resulting from a reaction. The noun form is das Reagieren, and related terms include die Reaktion (the reaction) and reagierend (reactive).

Usage and syntax

In everyday language, reagieren takes a stimulus or situation as the reference point with the preposition auf: zum Beispiel, “Sie reagierte überrascht auf die Nachricht.” In scientific contexts, especially chemistry, reagieren is used with the preposition mit to denote a chemical reaction: “Stoff A reagiert mit Stoff B.” Other common expressions include “auf etwas reagieren” and, more generally, “jemandem gegenüber reagieren” (to respond to someone).

Grammar

Reagieren is a regular German verb. Present indicative forms: ich reagiere, du reagierst, er reagiert, wir reagieren, ihr reagiert, sie reagieren. Simple past: ich reagierte, du reagierstest, er reagierte, wir reagierten, ihr reagiertet, sie reagierten. Perfect tense uses haben: ich habe reagiert, du hast reagiert, er hat reagiert. The verb is not prefix-separable; it behaves as a standard verb with prepositional complements rather than separable prefixes.

Etymology and usage notes

The word is a loanword in German, largely modeled on the French réagir, itself from Latin roots around agere (to act). In German, reaktionen can be philosophical, psychological, or scientific in scope, but the core meaning remains consistent: to respond to a cause, stimulus, or input.

See also: Reaktion, Reaktionszeit, reaktiv, reagierend.