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hydro

[ hahy-droh ]
/ ˈhaɪ droʊ /
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noun, plural hy·dros for 2, 3.
Informal. hydroelectric power.
Informal. hydroplane.
British.
  1. a bathhouse, hotel, or resort catering to people taking mineral-water health cures; spa.
  2. an establishment furnishing hydrotherapy.
adjective
Informal. of, relating to, or furnishing water, water power, or hydroelectricity: funds for new hydro projects.
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Origin of hydro

1880–85; by shortening of compounds with hydro-1 (cf. -o); (def. 4) hydro-1 analyzed as an adj.

Other definitions for hydro (2 of 3)

hydro-1

a combining form meaning “water,” used in the formation of compound words: hydroplane; hydrogen.
Also especially before a vowel, hydr-1.

Origin of hydro-

1
<Greek, combining form of hýdōr water

Other definitions for hydro (3 of 3)

hydro-2

a combining form representing hydrogen in compound words, denoting especially a combination of hydrogen with some negative element or radical: hydrobromic.
Also especially before a vowel, hydr-2.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2022

WORDS THAT USE HYDRO-

What does hydro- mean?

Hydro– is a combining form used like a prefix that has two distinct senses.

The first of these senses is “water,” and this form of hydro– is often used in a variety of scientific and technical terms. Hydro– comes from Greek hýdōr, meaning “water.”

The second of these senses is “hydrogen,” and this form of hydro– is occasionally used in a variety of scientific terms, especially in chemistry. Hydrogen, the lightest of the elements, combines with oxygen to form water. The word hydrogen comes from French hydrogène. The suffix gen, or its equivalent in French, means “that which produces.” Hydrogen literally translates to “that which produces water.”

What are variants of hydro-?

When combined with words or word elements that begin with a vowel, hydro– becomes hydr, as in hydrant. Want to know more? Read our Words That Use article on hydr-.

Examples of hydro- with the sense “water”

One example of a scientific term that features the form hydro– to mean “water” is hydrolysis, “chemical decomposition in which a compound is split into other compounds by reacting with water.”

We know hydro– means “water,” and the lysis portion of the word refers to “release,” from Greek lýsis. Hydrolysis literally translates to “water release.”

What are some words that use the combining form hydro-?

What are some other forms that hydro– may be commonly confused with?

Break it down!

The combining form logy is used to name areas of study or branches of science. With this in mind, what does hydrology mean?

Examples of hydro- with the sense “hydrogen”

A scientific term from chemistry that features the form hydro– to mean “hydrogen” is hydrochloric acid, “a colorless or faintly yellow, corrosive, fuming liquid, HCl, used chiefly in chemical and industrial processes.”

The hydro– part of hydrochloric here represents “hydrogen.” The chloric part of the word means “of or containing chlorine in the pentavalent state.” Hydrochloric literally translates to “of or containing hydrogen and chlorine.”

What are some words that use the combining form hydro-?

What are some other forms that hydro– may be commonly confused with?

  • hyalo-
  • hypo-

Break it down!

A sulphate is a compound that contains sulphuric acid. With this in mind, what does the compound hydrosulphate contain?

How to use hydro in a sentence

British Dictionary definitions for hydro (1 of 4)

hydro1
/ (ˈhaɪdrəʊ) /

noun plural -dros
British (esp formerly) a hotel or resort, often near a spa, offering facilities for hydropathic treatment

British Dictionary definitions for hydro (2 of 4)

hydro2
/ (ˈhaɪdrəʊ) /

adjective
short for hydroelectric
noun
a Canadian name for electricity when it is supplied to a residence, business, institution, etc

British Dictionary definitions for hydro (3 of 4)

Hydro
/ (ˈhaɪdrəʊ) /

noun
(esp in Canada) a hydroelectric power company or board

British Dictionary definitions for hydro (4 of 4)

hydro-

sometimes before a vowel hydr-


combining form
indicating or denoting water, liquid, or fluidhydrolysis; hydrodynamics
indicating the presence of hydrogen in a chemical compoundhydrochloric acid
indicating a hydroidhydrozoan

Word Origin for hydro-

from Greek hudōr 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

Medical definitions for hydro

hydro-

pref.
Water; liquid:hydrocephalus.
Hydrogen:hydrochloride.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Scientific definitions for hydro

hydro-

A prefix that means: “water” (as in hydroelectric) or “hydrogen,” (as in hydrochloride).
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
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