n. [ L. aether, Gr. a'iqh`r, fr. a'i`qein to light up, kindle, burn, blaze; akin to Skr. idh, indh, and prob. to E. idle: cf. F. éther. ] [ Written also æther. ] 1. (Physics) A medium of great elasticity and extreme tenuity, once supposed to pervade all space, the interior of solid bodies not excepted, and to be the medium of transmission of light and heat; hence often called luminiferous ether. It is no longer believed that such a medium is required for the transmission of electromagnetic waves; the modern use of the term is mostly a figurative term for empty space, or for literary effect, and not intended to imply the actual existence of a physical medium. However. modern cosmological theories based on quantum field theory do not rule out the possibility that the inherent energy of the vacuum is greater than zero, in which case the concept of an ether pervading the vacuum may have more than metaphoric meaning. [ 1913 Webster +PJC ]

2. Supposed matter above the air; the air itself. [ 1913 Webster ]

3. (Chem.) (a) A light, volatile, mobile, inflammable liquid, (C2H5)2O, of a characteristic aromatic odor, obtained by the distillation of alcohol with sulphuric acid, and hence called also sulphuric ether. It is a powerful solvent of fats, resins, and pyroxylin, but finds its chief use as an anæsthetic. Commonly called ethyl ether to distinguish it from other ethers, and also ethyl oxide. (b) Any similar compound in which an oxygen atom is bound to two different carbon atoms, each of which is part of an organic radical; as, amyl ether; valeric ether; methyl ethyl ether. The general formular for an ether is ROR′, in which R and R′ are organic radicals which may be of similar or different structure. If R and R′ are different parts of the same organic radical, the structure forms a cyclic ether. [ 1913 Webster +PJC ]

Complex ether,
Mixed ether (Chem.), an ether in which the ether oxygen is attached to two radicals having different structures; as, ethyl methyl ether, C2H5.O.CH3. --
Compound ether (Chem.), an ethereal salt or a salt of some hydrocarbon as the base; an ester. --
Ether engine (Mach.), a condensing engine like a steam engine, but operated by the vapor of ether instead of by steam. [ 1913 Webster ]

a. 1. Pertaining to the hypothetical upper, purer air, or to the higher regions beyond the earth or beyond the atmosphere; celestial; as, ethereal space; ethereal regions. [ 1913 Webster ]

Go, heavenly guest, ethereal messenger. Milton. [ 1913 Webster ]

2. Consisting of ether; hence, exceedingly light or airy; tenuous; spiritlike; characterized by extreme delicacy, as form, manner, thought, etc. [ 1913 Webster ]

Vast chain of being, which from God began,
Natures ethereal, human, angel, man. Pope. [ 1913 Webster ]

3. (Chem.) Pertaining to, derived from, or resembling, ether; as, ethereal salts. [ 1913 Webster ]

Ethereal oil. (Chem.) See Essential oil, under Essential. --
Ethereal oil of wine (Chem.), a heavy, yellow, oily liquid consisting essentially of etherin, etherol, and ethyl sulphate. It is the oily residuum left after etherification. Called also heavy oil of wine (distinguished from oil of wine, or œnanthic ether). --
Ethereal salt (Chem.), a salt of some organic radical as a base; an ester. [ 1913 Webster ]

n. Ethereality. [ 1913 Webster ]

n. The state of being ethereal; etherealness. [ 1913 Webster ]

Something of that ethereality of thought and manner which belonged to Wordsworth's earlier lyrics. J. C. Shairp. [ 1913 Webster ]

n. An ethereal or spiritlike state. J. H. Stirling. [ 1913 Webster ]

v. t. 1. To convert into ether, or into subtile fluid; to saturate with ether. [ 1913 Webster ]

2. To render ethereal or spiritlike. [ 1913 Webster ]

Etherealized, moreover, by spiritual communications with the other world. Hawthorne. [ 1913 Webster ]

adv. In an ethereal manner. [ 1913 Webster ]

n. Ethereality. [ 1913 Webster ]

a. [ L.aethereus, Gr. &unr_; See Ether. ] 1. Formed of ether; ethereal. [ Obs. ] [ 1913 Webster ]

This ethereous mold whereon we stand. Milton. [ 1913 Webster ]

2. (Chem.) Pertaining to, or resembling, ether. [ 1913 Webster ]

Ethereous oil. See Ethereal oil, under Ethereal. [ 1913 Webster ]

n. (Chem.) The act or process of making ether; specifically, the process by which a large quantity of alcohol is transformed into ether by the agency of a small amount of sulphuric, or ethyl sulphuric, acid. [ 1913 Webster ]