Pronunciation: (ē'thur),[key] —n. 1. Also calleddiethyl ether,diethyl oxide,ethyl ether,ethyl oxide,sulfuric ether.Chem.,Pharm.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. Chem.(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. Cf. Michelson-Morley experiment.Also,aether(for defs. 3–5).