dehydrate

Dehydrate is a verb meaning to remove water from something. The noun dehydration refers to the state or process of losing water. The term is used in chemistry, biology, and everyday contexts such as food preservation. Etymology traces to Latin de- meaning removal together with Greek hydor meaning water.

In chemistry, dehydration denotes a reaction in which water is eliminated from a molecule. Common examples include the dehydration of alcohols to form alkenes, such as converting ethanol to ethene, typically with acid catalysts like concentrated sulfuric acid or dehydrating agents such as phosphorus oxychloride.

In biology and medicine, dehydration describes a deficit of body water. Causes include inadequate fluid intake, heavy sweating, diarrhea or vomiting, fever, or certain illnesses. Symptoms include thirst, dry mouth, reduced urination, dark urine, dry skin, dizziness, or confusion in severe cases. Risk groups include young children, older adults, and people with chronic illnesses. Treatment ranges from oral rehydration solutions to intravenous fluids in severe cases.

In food processing and storage, dehydration is used to preserve and concentrate foods. Methods include air drying, sun drying, freeze-drying (lyophilization), vacuum drying, and spray drying. Lower moisture inhibits microbial growth and enzymatic activity. Rehydration is often possible by soaking dried foods.

Related concepts include dehydration synthesis, a chemical reaction that forms bonds by removing water, and hydration, the chemical addition of water.