Noun

(en noun)

(Christianity) A Christian feast commemorating the resurrection of Christ; the first Sunday following the full moon that occurs on or next after the vernal equinox, neither earlier than March 22 nor later than April 25.

We spent each of the past five Easters together as a family.

Eastertide

(obsolete) The Jewish passover.

* 1526 , William Tyndale, trans. Bible , Mark XIV:

After two dayes folowed ester , and the dayes of swete breed.

(paganism) A festival held in honour of the goddess Eostre or Ostara and celebrated at the spring equinox or within the month of April. Also known as Eostre.

Noun

(organic compound, countable) A compound containing an oxygen atom bonded to two hydrocarbon groups.

(organic compound, uncountable) Diethyl ether (C₄H₁₀O), a compound used as an early anaesthetic.

(ancient philosophy, and, alchemy, uncountable) A classical physical element, considered as prevalent in the heavens and inaccessible to humans. In some versions of alchemy, this was the fifth element in addition to air, earth, fire and water.

(archaic, physics, uncountable) A substance (aether ) once thought to fill all space that allowed electromagnetic waves to pass through it and interact with matter, without exerting any resistance to matter or energy (disproved by Einstein in his Theory of Relativity).

* {{quote-magazine, date=2013-06-14, author=(Jonathan Freedland)

, volume=189, issue=1, page=18, magazine=(The Guardian Weekly) , title= Obama's once hip brand is now tainted , passage=Now we are liberal with our innermost secrets, spraying them into the public ether with a generosity our forebears could not have imagined. Where we once sent love letters in a sealed envelope, or stuck photographs of our children in a family album, now such private material is despatched to servers and clouds operated by people we don't know and will never meet.}}

The sky or heavens; the upper air.