Reduce

To thicken and intensify the flavor of a liquid by rapidly boiling the contents in an uncovered pan in order to evaporate excess liquid. This process is used generally on soups and sauces. This process is similar to deglazing, but is not the same. When reducing, the liquid contents are boiled in order to evaporate and reduce the volume of liquid so that the remaining contents are thicker and more flavorful. If a recipe suggests reducing the sauce by a half, simmer the liquid to a half of the original volume is removed by boiling off the lighter liquid contents. Deglazing involves less reduction and a slower cooking of the contents.