ether

noun

ˈē-thər 

1

a

: the rarefied element formerly believed to fill the upper regions of space

b

: the upper regions of space : heavens

2

a

: a light volatile flammable liquid C₄H₁₀O used chiefly as a solvent and especially formerly as an anesthetic

b

: any of a class of organic compounds characterized by an oxygen atom attached to two carbon atoms

3

a

or less commonly aether

ˈē-thər 

: a medium that in the wave theory of light permeates all space and transmits transverse waves

b

: airwaves

etheric

i-ˈther-ik 

-ˈthir-

adjective

Examples of ether in a Sentence

The balloon disappeared into the ether.

Recent Examples on the Web

Unlike bitcoin, ether and other cryptocurrencies, stablecoins are designed to have a stable value against a non-crypto asset, usually the U.S. dollar. —Tanaya MacHeel, CNBC, 23 Apr. 2025

And a January 2020 study indicated that one flame retardant—polybrominated diphenyl ethers, or PBDEs—could affect a child’s intellectual development.4 That’s not to say nothing is being done or that zero guardrails are in place. —Beth Ann Mayer, Parents, 23 Apr. 2025

After a series of trials with ether, Morton conducted a public demonstration, which successfully numbed the patient’s pain and marked a major breakthrough in medical practice. —Ella Jeffries, Smithsonian Magazine, 8 Apr. 2025

Fidelity is already tinkering with a stablecoin under its digital assets division, which currently offers custody and trading for bitcoin, ether and litecoin. —Nina Bambysheva, Forbes.com, 27 Mar. 2025

Word History

Etymology

Middle English, from Latin aether, from Greek aithēr, from aithein to ignite, blaze; akin to Old English ād pyre — more at edify

First Known Use

14th century, in the meaning defined at sense 1a

Phrases Containing ether

• diethyl ether
• ether extract
• ethyl ether
• into the ether
• over/through the ether
• the ether

Kids Definition

ether

noun

ˈē-thər 

1

a

: an invisible substance once believed to fill the upper regions of space

b

: the upper regions of space : heavens

2

: an easily evaporated flammable liquid used chiefly to dissolve other substances and especially formerly as an anesthetic

Medical Definition

ether

noun

ˈē-thər 

1

: a medium that in the wave theory of light permeates all space and transmits transverse waves

2

a

: a light volatile flammable liquid C₄H₁₀O used especially formerly chiefly as an anesthetic

called also diethyl ether, ethyl ether, ethyl oxide

b

: any of various organic compounds characterized by an oxygen atom attached to two carbon atoms