Which term describes a substance that lowers the amount of energy needed to start chemical reaction?

The substances that lower the amount of energy needed to star a chemical reaction are called catalysts.

The catalyst speeds up a reaction by creating an intermediate within the reaction. By the end of the reaction, the catalyst is regenerated and ready to speed up the next reaction.

One of the most famous catalysts are enzymes, proteins that are necessary for many chemical reaction in biological systems. Some of the catalysts can be much simpler than the proteins, and often are simple salts or metals.