What term describes a substance that alters the rate of a chemical reaction without being consumed or permanently changed?

A catalyst is a substance that increases or decreases the rate of a chemical reaction without undergoing any permanent change itself. This means that it facilitates the reaction by providing an alternative pathway with a lower activation energy, allowing the reactants to convert into products more efficiently. Importantly, since a catalyst is not consumed in the reaction, it can be used repeatedly.

In contrast, a reactant is a substance that undergoes a change during the reaction, meaning it is consumed in the process. An inhibitor slows down the reaction rate but is not a substance that facilitates or speeds up the reaction. Enzymes are biological catalysts that perform the same function as a general catalyst, but they are specific to biological processes. While enzymes are a type of catalyst, the broader term that encompasses all such substances is catalyst. Therefore, identifying a catalyst as the correct answer accurately captures the essence of the term described in the question.