e·ther

/ˈi
θər/ Pronunciation Key - Show Spelled Pronunciation[ee-ther] Pronunciation Key - Show IPA Pronunciation –noun 1.Also called diethyl ether, diethyl oxide, ethyl ether, ethyl oxide, sulfuric ether. Chemistry, Pharmacology. a colorless, highly volatile, flammable liquid, C4H10O, 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. Also, aether (for defs. 3–5).