What does rehydration mean?
Rehydration is the process of restoring lost fluid, especially to the human body after dehydration caused by illness, heat, exercise, or inadequate intake. In medical contexts, rehydration may involve drinking an oral rehydration solution, which combines water with salts and often glucose so that fluid and electrolytes can be absorbed effectively. Severe cases may require intravenous fluids. The word can also be used more broadly for replenishing depleted resources or restoring something to a previous condition, although this figurative sense is less common. Rehydration is closely related to hydration but is more specific: hydration describes maintaining or supplying adequate fluid, while rehydration emphasizes replacing fluid that has already been lost. The term is important in medicine, sports science, food technology, and environmental contexts.
The process of restoring fluid or moisture to a person, organism, or material that has lost it.
"Careful rehydration is essential for treating severe dehydration."
Medical and nutritional contexts commonly distinguish oral rehydration from intravenous rehydration.
The broader restoration of supplies, resources, or a previous condition.
"The project was designed to support the rehydration of depleted wetlands."
Usually used in specialist or technical contexts when referring to separate instances of the process.
"The report compares different approaches to rehydrations of contaminated soil."
Oral rehydration solution has helped treat dehydration caused by diarrheal disease, one of the leading causes of preventable death in children worldwide.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does rehydration come from?
Rehydration was formed in the 19th century by combining the prefix re-, meaning “again,” with hydration, a derivative of hydrate. Hydrate ultimately comes from Greek hydōr, meaning “water,” through Latin hydrō-, and is related to hydrogen. The prefix re- distinguishes the restoration of a previously hydrated state from the initial process of hydration.
Related word forms
How rehydration is actually used
In medicine and nutrition, the term most often refers to replacing water and electrolytes lost through dehydration. Its broader figurative use is less formal and usually describes the restoration of energy, resources, or supplies.
Easily confused with rehydration
Hydration is the condition of having adequate fluid or the process of supplying fluid, whereas rehydration specifically involves restoring a person or material that has already lost fluid.