Why are enzymes called catalysts if they are proteins and not chemicals?

A catalyst refers to many types of different molecules or chemicals which can reduce the activation energy of a reaction without being used up itself. Activation energy is the minimum energy required for a reaction to take place and in reducing this, a catalyst can increase the rate of reaction. Enzymes are proteins in organisms which can carry out this function. They will bind to a substrate via their active sites and reduce the activation energy of the reaction in question which could be a number of different metabolic processes. When the reaction has taken place, the products will be released from the active site, and the enzyme will be ready to catalyse another reaction with its own structure and function unchanged. To summarise, whether it is a protein or an acid or an ion, if it can speed up the rate of reaction by reducing the activation energy without being used up or changed itself, it is a catalyst.