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

REACTION definition: a reverse movement or tendency; an action in a reverse direction or manner. See examples of reaction used in a sentence.

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 …

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

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

Look up reaction in Wiktionary, the free dictionary. Reaction may refer to a process or to a response to an action, event, or exposure.

Dec 14, 2025 · reaction (plural reactions) An action or statement in response to a stimulus or other event.

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. A reaction against something is a way of …

Online reaction time test. Click as soon as the field turns green. Average and best time, attempts, CSV export, and built‑in self‑tests.

Improve your reaction time with our reaction time test. Measure your response speed and compare it with others. Take the test now on our website.