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.
Mella said that protecting large, shade-producing trees or providing access to water during heatwaves could help reduce dehydration risk among koalas.
From Barron's • May 26, 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
“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
There were constant hazards to be wary of, from polar bears to frostbite and cold-weather dehydration.
From BBC • Apr. 12, 2026
A fear of the cracked tongue, aching body and fuzzy mind brought on by my previous dehydration creeps into my consciousness.
From "The Hunger Games" by Suzanne Collins
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.
