Reduction (cooking)

process of thickening and intensifying the flavor of a liquid mixture such as a soup, sauce, wine, or juice by simmering or boiling

In cooking, a reduction is a sauce or liquid that has been thickened by heating it slowly. The heat causes some of the water in the sauce to evaporate, making it thicker and have a stronger taste.[1]

References

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  1. "What is a reduction?". Spruce Eats.