<p><strong>Noun</strong></p><ul><li>Also called diethyl ether</li><li>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</li><li>(formerly) one of a class of compounds in which two organic groups are attached directly to an oxygen atom, having the general formula ROR</li><li>the upper regions of space; the clear sky; the heavens</li><li>the medium supposed by the ancients to fill the upper regions of space</li><li>Physics: a hypothetical substance supposed to occupy all space, postulated to account for the propagation of electromagnetic radiation through space</li></ul>