ether

American  

[ee-ther] / ˈi θər /

Also aether

noun

• ethers
  plural

1. Also called sulfuric ether.  Also called diethyl ether.  Also called ethyl ether,.  Also called diethyl oxide,.  Also called ethyl oxide,.  Chemistry, Pharmacology. a colorless, highly volatile, flammable liquid, C 4 H 10 O, having an aromatic odor and sweet, burning taste, derived from ethyl alcohol by the action of sulfuric acid: used as a solvent and, formerly, as an inhalant anesthetic.

2. Chemistry. (formerly) one of a class of compounds in which two organic groups are attached directly to an oxygen atom, having the general formula ROR.

3. the upper regions of space; the clear sky; the heavens.

4. the medium supposed by the ancients to fill the upper regions of space.

5. Physics. a hypothetical substance supposed to occupy all space, postulated to account for the propagation of electromagnetic radiation through space.

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ether British  

/ ˈiːθə, iːˈθɛrɪk /

noun

1. Also called: diethyl ether.   ethyl ether.   ethoxyethane.  a colourless volatile highly flammable liquid with a characteristic sweetish odour, made by the reaction of sulphuric acid with ethanol: used as a solvent and anaesthetic. Formula: C 2 H 5 OC 2 H 5

2. any of a class of organic compounds with the general formula ROR′ where R and R′ are alkyl groups, as in diethyl ether C 2 H 5 OC 2 H 5

3. the hypothetical medium formerly believed to fill all space and to support the propagation of electromagnetic waves

4. Greek myth the upper regions of the atmosphere; clear sky or heaven

5. a rare word for air

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ether Scientific  

/ ē′thər /

1. An organic compound in which two hydrocarbon groups are linked by an oxygen atom, having the general structure ROR|||PRIMARY_STRESS|||, where R and R|||PRIMARY_STRESS||| are the two hydrocarbon groups. At room temperature, ethers are pleasant-smelling liquids resembling alcohols but less dense and less soluble in water. Ethers are part of many naturally occurring organic compounds, such as starches and sugars, and are widely used in industry and in making pharmaceuticals.

2. A colorless, flammable liquid used as a solvent and formerly used as an anesthetic. Ether consists of two ethyl groups joined by an oxygen atom. Also called diethyl ether, ethyl ether. Chemical formula: C ₄ H ₁₀ O.

3. A hypothetical medium formerly believed to permeate all space, and through which light and other electromagnetic radiation were thought to move. The existence of ether was disproved by the American physicists Albert Michelson and Edward Morley in 1887.

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Other Word Forms

Derived Forms

• superether
  noun
• etheric
  adjective

Inflected Forms

Nouns

• ethers
  plural

Etymology

Origin of ether

First recorded in 1350–1400; Middle English, from Latin aethēr “the upper air, pure air, ether,” from Greek aithḗr, akin to aíthein “to glow, burn,” Old English ād “funeral pyre,” Latin aestus “heat”

Explanation

Ether is a chemical that used to be a common anesthetic that you inhaled before undergoing surgery. In most countries, doctors have replaced it with less flammable, safer drugs. The chemical ether is a colorless liquid that's still used as an anesthetic in some developing countries and as an industrial solvent. The Latin root is aether, which means "the upper pure, bright air." Ether was originally a scientific term for what 19th century physicists called "the fifth element," a substance that was said to fill all space and make up all bodies. In modern times, ether has come to be a literary term that refers to the sky.

Example Sentences

See Examples For:

ether ethers

But when Kore-eda’s execution isn’t as assured, as is the case with his latest, all that delicacy simply floats off into the ether, rarely amounting to much more than a halfhearted shrug.

From Los Angeles Times ● Jul. 24, 2026

Anderson splits his time between Japan and Indonesia, and said he was able to retire a few years ago after investing in bitcoin, ether and precious metals.

From The Wall Street Journal ● Jul. 16, 2026

"The thought of all that money, all that time that I've saved up, that excitement completely vanishing into the ether, it was terrifying," he says.

From BBC ● Jul. 11, 2026

While bitcoin and ether still have much larger trading volumes on Hyperliquid than most other markets, the more telling shift is where activity is growing fastest, as shown by the chart below.

From MarketWatch ● Jun. 10, 2026

What have you done with the ether, Sister?

From "And Then There Were None" by Agatha Christie

Their proliferation might not affect the sheer number of bitcoins, ethers and other tokens, but some investors thought their arrival has dented bitcoin’s appeal as a scarce asset.

From The Wall Street Journal ● Feb. 7, 2026

Other EDCs of concern include organophosphate ethers, benzotriazoles, and PBDEs, all of which are used to make plastic products fire- and light-resistant.

From Salon ● Apr. 2, 2024

In the study, the team used ring-shaped molecular structures called "crown ethers," which contain benzene and bromine rings.

From Science Daily ● Jan. 30, 2024

The research found the levels of banned PBDEs, or polybrominated diphenyl ethers, in breast milk have declined some 70% over the past two decades.

From Seattle Times ● Jul. 21, 2023

A mixture of α- and β-glucose result, which are then etherified, and if the solution be neutralized before the β-form isomerizes and the solvent removed, a mixture of the α- and β-methyl ethers is obtained.

From Encyclopaedia Britannica, 11th Edition, Volume 12, Slice 2 "Gloss" to "Gordon, Charles George" by Various