The meaning of REACTION is the act or process or an instance of reacting. How to use reaction in a sentence.

A chemical reaction is the change that happens when two or more substances are mixed with each other.

Explore what makes a reaction happen by colliding atoms and molecules. Design experiments with different reactions, concentrations, and temperatures. When are reactions reversible? What affects …

Usage: Reaction is used to refer both to an instant response (her reaction was one of amazement) and to a considered response in the form of a statement (the Minister gave his reaction to the court's …

A reaction is an action taken in response to something. If you're telling your parents that you want to move out, you'll see by their reaction that they're sad about it.

Your reaction to something that has happened or something that you have experienced is what you feel, say, or do because of it. Reaction to the visit is mixed.

Jan 20, 2026 · Noun reaction (plural reactions) An action or statement in response to a stimulus or other event.