What is a hygroscopic substance used primarily as a drying agent called?

A hygroscopic substance used primarily as a drying agent is termed a desiccant. Desiccants are materials that absorb moisture from the air and are often utilized in various applications to keep products dry. For instance, they are commonly found in packages to prevent moisture damage, in laboratories to maintain dry conditions, and in food preservation to enhance shelf life.

Each of the other terms listed refers to different functions in the context of pest management and chemical applications. An insecticide is a chemical agent used to kill insects, while an adjuvant is an additive used in pesticide formulation to enhance the efficacy of the active ingredient. A surfactant is a substance that reduces surface tension, allowing liquids to spread more easily and improve the coverage and adhesion of pesticides. None of these terms relate to the moisture-absorbing properties of a desiccant.