hydration

Etymology

It is formed from English hydrate + -ation,^[2][3] or, in Merriam-Webster's analysis, from hydrate and the suffix -ion;^[4][5] Etymonline suggests it may also come from French hydration.^[6] The chemical noun hydrate is from hydrate, coined about 1800 by the French chemist Joseph-Louis Proust^[6][7] from Ancient Greek ὕδωρ (húdōr, “water”) and the suffix -ate.^[2][7][8] Etymonline traces the Greek word to a suffixed form of Proto-Indo-European *wed- (“water; wet”).^[6] The verb hydrate, to combine chemically with water, is recorded from 1812, implied in the past participle.^[6]

Earliest recorded meaning

Combination with water; the action of hydrating something, or the condition of being hydrated: Etymonline dates the word to 1823,^[6] and the OED's first quotation is from 1854, in J. Scoffern's contribution to Orr's Circle of the Sciences.^[2]

Semantic evolution

The word began as a term of chemistry, for the chemical combination of water with another substance,^[2][3][4] and the Shorter Oxford dates it to the mid 19th century.^[3] Merriam-Webster narrows the chemical sense to a reaction in which water takes part, especially in the form of whole molecules, and in which only one product is formed.^[4] Etymonline dates the use of the verb hydrate for restoring moisture to 1947,^[6] and the noun now also covers the supply of enough fluid to the body and its tissues.^[4][1] The setting of cement, in which it combines with water and gives off heat, is also called hydration.^[1]

Timeline

• 1823 – combination with water, as the noun of action of the verb hydrate.^[6] The OED's first quotation is from 1854.^[2]

Meanings

Noun

1. The process of combining with water, or the state of being combined with it: Hydration makes the dried clay swell again.^[2][3][4]
2. A chemical reaction in which water molecules are added to another compound to form a single product.^[4][1]
3. The supply of enough water or fluid to the body or its tissues: Good hydration matters on a long hike.^[4][1]
4. The reaction by which cement combines with water and hardens, giving off heat.^[1]

Word family

• dehydration
• water of hydration

Related words

• hydrate
• dehydrate
• hydro-
• water

References

1. ^ a b c d e f Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d e f Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
3. ^ a b c d Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
4. ^ a b c d e f g Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
5. ^ Gove, Philip Babcock, ed. (1961), Webster's Third New International Dictionary of the English Language, Unabridged, Springfield, Mass.: G. & C. Merriam
6. ^ a b c d e f g Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
7. ^ a b Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
8. ^ Hoad, T. F., ed. (1986), The Concise Oxford Dictionary of English Etymology, Oxford: Clarendon Press