What does dehydrate mean?
Dehydrate is a verb meaning to remove water from something, whether deliberately for preservation or as the harmful result of heat, illness, or exertion. In kitchens and industry, dehydrating is a controlled technique: fruits, vegetables, meat, and even instant coffee are dehydrated to extend shelf life and reduce weight, yielding familiar products such as dried apricots, jerky, and powdered milk. In medicine, dehydrate describes the loss of water from a living body — a person may become dehydrated through fever, vomiting, extreme heat, or simply failing to drink enough — and severe dehydration is a serious condition requiring prompt treatment, sometimes with intravenous fluids. The word carries a neutral, technical tone when describing food processing but a cautionary one in health contexts. Its derivatives include dehydration, dehydrated, and dehydrator, and its opposite, rehydrate, restores what dehydration removes.
verbTo remove water from something, typically in order to preserve it or dry it out. In medicine, to cause (a body or organism) to lose excessive water, or to lose water from the body itself.
- To remove water from something, especially as a means of preservation (e.g. dehydrated food).
- To lose or cause an organism to lose dangerous amounts of water from the body.
"The intense heat of the desert can dehydrate a hiker within hours."
"Backpackers favour dehydrated meals because they weigh almost nothing."
"After the marathon, several runners were so dehydrated they needed intravenous fluids."
Remove the water and you remove the life — the same process that turns grapes into raisins can turn a healthy body into a medical emergency.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of dehydrate
Dehydrate was formed in English in the early 19th century from the Greek root hydōr, meaning 'water', combined with the prefix de-, indicating removal, via French déshydrater. It belongs to a large family of scientific terms built on that Greek root, including hydrogen ('water-forming'), hydraulic ('water-driven'), and hydrant. The word entered general use alongside the growth of chemistry and food-preservation science in the 1800s.
Word family
Usage notes
Common in both everyday and scientific registers. The reflexive or passive form 'to become dehydrated' is the usual way to describe bodily fluid loss; the active 'the heat dehydrated him' is also fully standard.
Don't confuse with
Rehydrate means to restore lost water to something, whereas dehydrate means to remove water from it.