hydro-

¹

1. a combining form meaning “water,” used in the formation of compound words:

   hydroplane; hydrogen.

hydro-

²

1. a combining form representing hydrogen in compound words, denoting especially a combination of hydrogen with some negative element or radical:

   hydrobromic.

hydro

³

[ hahy-droh ]

noun

, plural hy·dros

1. Informal. hydroelectric power.
2. Informal. hydroplane.
3. British.
   1. a bathhouse, hotel, or resort catering to people taking mineral-water health cures; spa.
   2. an establishment furnishing hydrotherapy.

adjective

1. Informal. of, relating to, or furnishing water, water power, or hydroelectricity:

   funds for new hydro projects.

hydro

¹

/ ˈhaɪdrəʊ /

adjective

1. short for hydroelectric

noun

1. a Canadian name for electricity when it is supplied to a residence, business, institution, etc

Hydro

²

/ ˈhaɪdrəʊ /

noun

1. (esp in Canada) a hydroelectric power company or board

hydro

³

/ ˈhaɪdrəʊ /

noun

1. (esp formerly) a hotel or resort, often near a spa, offering facilities for hydropathic treatment

hydro-

⁴

combining_form

1. indicating or denoting water, liquid, or fluid

   hydrodynamics

   hydrolysis

2. indicating the presence of hydrogen in a chemical compound

   hydrochloric acid

3. indicating a hydroid

   hydrozoan

hydro–

1. A prefix that means: “water” (as in hydroelectric ) or “hydrogen,” (as in hydrochloride ).

Word History and Origins

Origin of hydro-¹

< Greek, combining form of hýdōr water

Origin of hydro-²

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

Word History and Origins

Origin of hydro-¹

from Greek hudōr water

Example Sentences

Canada has abundant hydro potential — and in fact Manitoba and Quebec have abundant hydro for sale right now.

From The Daily Beast

Here, however, it's worth noting that heavy use of emissions-free hydro power correlates strongly with lower power rates.

From The Daily Beast

Alaska Electric Light and Power got a 24 percent residential rate hike to deal with inflation and to build a new hydro project.

From The Daily Beast

A large number of these mills are actuated hydraulically or hydro-electrically.

From Project Gutenberg

The hydro-electric industry has been largely nationalized by those who are foremost in it.

From Project Gutenberg

Retinol, ret′i-nol, n. a hydro-carbon oil used in printers' ink.

From Project Gutenberg

Next to my flight in the hydro-aeroplane this was the greatest experience of my life.

From Project Gutenberg

On this supposition the positive impulse is to be regarded as hydro-mechanical.

From Project Gutenberg

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-?

• hydrofoil
• hydrogen (using the equivalent form of hydro– in French)
• hydrology
• hydrophobia (using the equivalent form of hydro– in Greek)
• hydroplane
• hydrotropic

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

• hyalo-
• hypo-

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-?

• hydrobromic
• hydrocarbon
• hydrocyanic
• hydrodesulfurization
• hydrosulphate

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?