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hydrate

American  
[hahy-dreyt] / ˈhaɪ dreɪt /

noun

  • hydrates
    plural
  1. any of a class of compounds containing chemically combined water. In the case of some hydrates, as washing soda, Na 2 CO 3 ⋅10H 2 O, the water is loosely held and is easily lost on heating; in others, as sulfuric acid, SO 3 ⋅H 2 O, or H 2 SO 4 , it is strongly held as water of constitution.


verb (used with or without object)

  • hydrates,
    present (3rd person singular)
  • hydrated,
    past participle,  past
  • hydrating
    present participle
  1. to combine chemically with water.

hydrate British  
/ ˈhaɪdreɪt /

noun

  1. a chemical compound containing water that is chemically combined with a substance and can usually be expelled without changing the constitution of the substance

  2. a chemical compound that can dissociate reversibly into water and another compound. For example sulphuric acid (H 2 SO 4 ) dissociates into sulphur trioxide (SO 3 ) and water (H 2 O)

  3. (not in technical usage) a chemical compound, such as a carbohydrate, that contains hydrogen and oxygen atoms in the ratio two to one

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

verb

  1. to undergo or cause to undergo treatment or impregnation with water

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
hydrate Scientific  
/ hīdrāt′ /
  1. A compound produced by combining a substance chemically with water. Many minerals and crystalline substances are hydrates.


  1. To combine a compound with water, especially to form a hydrate.

  2. To supply water to a person in order to restore or maintain a balance of fluids.

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Etymology

Origin of hydrate

First recorded in 1795–1805; hydr- 1 + -ate 2

Explanation

To hydrate is to add or absorb water. It's hot outside — don't forget to hydrate by drinking plenty of water! If you want to sound fancy, you can use the word hydrate every time you get a drink of water. Along with most organisms, we need to hydrate, or ingest water, to stay alive. This verb is also commonly used to mean "moisturize," as in "this magic cream will hydrate your skin like you won't believe!" As a noun, hydrate refers to a chemical compound that includes water molecules. A French chemist coined the noun in 1800 from the Greek hydor, "water."

Keep Reading on Vocabulary.com

Vocabulary lists containing hydrate

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.

See Examples For:

Despite those conditions, the sodium vanadate hydrate continued to work effectively.

From Science Daily Aug. 1, 2026

The word hydrate means that water molecules are built into the material's structure.

From Science Daily Aug. 1, 2026

Instead, the medical provider may just tell their patient to keep an eye on their symptoms, wait and hydrate.

From Los Angeles Times Jul. 24, 2026

Other fruits that can help hydrate you are berries, peaches and citrus fruits, she says.

From BBC Jun. 25, 2026

I gag thinking about where they’ll get the liquid to hydrate the meals.

From "The Last Cuentista" by Donna Barba Higuera

Methanol helps prevent freezing and the accumulation of solid hydrates that can plug gas-compression equipment and limit pipeline flow, and it acts as a solvent and corrosion inhibitor.

From The Wall Street Journal Nov. 21, 2025

Water, the main ingredient in most sports drinks, hydrates you.

From Salon Jan. 21, 2025

The challenge now is making sure everyone hydrates well to recover as quickly as possible.

From Washington Times Dec. 29, 2023

Researchers have previously studied how changes in bottom water temperature near continental margins can affect the release of methane from hydrates.

From Science Daily Dec. 6, 2023

The parts that remain are likely to be converted into oxides, carbonates, and hydrates, through reaction with oxygen, carbon dioxide, and water, which are always present at the surface and at shallow depths.

From The Economic Aspect of Geology by C. K. (Charles Kenneth) Leith

The hydrated material stored far more charge, charged much faster, and continued to perform reliably for more than 400 charge cycles.

From Science Daily Aug. 1, 2026

"We are urging people to stay hydrated and use air conditioners," a fire brigade spokesman told AFP.

From Barron's Jul. 23, 2026

What’s more, staying hydrated helps flush toxins, keeps organs functioning optimally and thins mucus, making it easier for lungs to stay clear.

From The Wall Street Journal Jul. 23, 2026

For those who need to wait for assistance, she said advice is also offered on keeping them hydrated, fed and comfortable.

From BBC Jul. 15, 2026

On one website, we find a list of supplies every dog walker should own: a spare leash, lots of baggies, and a reusable water bottle and plastic bowl to keep the dogs hydrated.

From "A Soft Place to Land" by Janae Marks

Dietitian Kate Hilton says she's drinking more iced water and eating cool, hydrating foods like cucumber, tomatoes, melon and frozen smoothies.

From BBC Jun. 25, 2026

The fruit is also made up of about 92% water, making it a hydrating option during hot weather or after exercise.

From Science Daily May 17, 2026

WSJ | Buy Side: Using powerful but gentle ingredients, this body wash kills bacteria while soothing and hydrating skin.

From The Wall Street Journal May 6, 2026

That brief chill allows the fat to firm and the panade to finish its quiet work, hydrating and binding.

From Salon Mar. 11, 2026

Be sure to moisturize with an ultra- hydrating serum like The Corporation’s new Skin So Right B14 Complex for Total Cell Renewal, made with essential vitamins, minerals, and concentrated yak’s bladder.

From "Beauty Queens" by Libba Bray

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