[ hahy-dreyt ]

  1. any of a class of compounds containing chemically combined water. In the case of some hydrates, as washing soda, Na2CO3⋅10H2O, the water is loosely held and is easily lost on heating; in others, as sulfuric acid, SO3⋅H2O, or H2SO4, it is strongly held as water of constitution.

verb (used with or without object),hy·drat·ed, hy·drat·ing.
  1. to combine chemically with water.

Origin of hydrate

First recorded in1795–1805; hydr-1 + -ate2

Other words from hydrate

  • hy·dra·tion, noun

Words Nearby hydrate

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2024

How to use hydrate in a sentence

British Dictionary definitions for hydrate


/ (ˈhaɪdreɪt) /

  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)

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

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

Origin of hydrate

C19: from hydro- + -ate 1

Derived forms of hydrate

  • hydration, noun
  • hydrator, noun

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

Scientific definitions for hydrate


[ drāt′ ]

  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.

The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.