The general term for a substance that speeds up a chemical reaction without being consumed by it is a catalyst. A catalyst increases reaction rate by providing an alternative reaction pathway with a lower activation energy.
Although a catalyst is regenerated by the overall reaction, it can still participate in intermediate steps. It may temporarily bond with reactants, form intermediate compounds, and then return to its original chemical state. Because it is not used up in the net reaction, even a relatively small amount can affect a large quantity of reactants.
Catalysts can be homogeneous, sharing a phase with the reactants, or heterogeneous, existing in a different phase. Enzymes are biological catalysts; for example, catalase rapidly breaks down hydrogen peroxide into water and oxygen. Industrial catalysts help manufacture fuels, fertilizers, plastics, and medicines.
A catalyst changes how quickly a reaction reaches equilibrium, but it does not change the equilibrium position itself. It also does not normally change the overall energy released or absorbed. Substances that slow reactions are called inhibitors, which is why inhibitor is not the correct answer here.