dehydration
Americannoun
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the act or process of dehydrating.
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an abnormal loss of water from the body, especially from illness or physical exertion.
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The process of losing or removing water or moisture.
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A condition caused by the excessive loss of water from the body, which causes a rise in blood sodium levels. Since dehydration is most often caused by excessive sweating, vomiting, or diarrhea, water loss is usually accompanied by a deficiency of electrolytes. If untreated, severe dehydration can lead to shock.
Etymology
Origin of dehydration
Explanation
Dehydration is what happens when something has water removed from it. Dehydration makes people extremely thirsty, and it can make plants grow droopy and brown. During dehydration, moisture is lost without being replaced. In humans, dehydration can happen during strenuous exercise or in extreme heat — or simply when someone doesn't drink enough water for a certain length of time. A grape becomes a raisin through dehydration, shriveling and drying as moisture is removed. Dehydration and dehydrate, first used only by scientists, have a Greek root, hydro, "water."
Vocabulary lists containing dehydration
Elements of the Universe: Hydr, Hydro ("Water")
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Dry
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hydr, hydro
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
This leads to dehydration and eventually “desertification”—a phenomenon the film tracks across a quasi-equatorial band of the Earth, where deforestation in pursuit of farmland has had a deleterious effect.
From The Wall Street Journal • Jun. 2, 2026
Experts also warn that prolonged fasting can increase the risk of dehydration, electrolyte imbalances, dizziness, muscle loss, and complications for people with underlying health conditions.
From Science Daily • May 17, 2026
Several studies have found high levels of dehydration, heat stress and even signs of kidney malfunction among these communities.
From Barron's • May 10, 2026
“I’d eat them at specific times. You go through periods of fasting and through dehydration whenever you had your top off. There was a real science to it.”
From Los Angeles Times • Apr. 23, 2026
In the spring the lower bank is underwater, but right now it’s August, when dehydration and sun sickness stalk the village.
From "Red Queen" by Victoria Aveyard
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
