a medium of great elasticity and extreme tenuity, 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.-supposed matter above the air; the air itself.-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 powerful solvent of fats, resins, and pyroxylin, but finds its chief use as an anaesthetic. called also ethyl oxide.-any similar oxide of hydrocarbon radicals; as, amyl ether; valeric ether.