ethereal

Etymology

From Latin aetherius (“of or pertaining to the ether, the sky, or the air or upper air”), from Ancient Greek αἰθέριος (aithérios, “of or pertaining to the upper air”). By surface analysis, ether + -ial.

adj

1. Pertaining to the (real or hypothetical) upper, purer air, or to the higher regions beyond the earth or beyond the atmosphere.
   ethereal space
   ethereal regions
   I trust that we shall be more imaginative, that our thoughts will be clearer, fresher, and more ethereal, as our sky,[…] 1862, Henry David Thoreau, “Walking”, in The Atlantic Monthly, volume 9, number 56
   She was very young—at the most nineteen, with a pale somewhat refined face, yellow hair, merry blue eyes, and shining teeth. Her beauty was of an ethereal type. 1885, Arthur Conan Doyle, The Man From Archangel
2. Pertaining to the immaterial realm, as symbolically represented by, or (in earlier epochs) conflated with, such atmospheric and extra-atmospheric concepts.
3. Consisting of ether; hence, exceedingly light or airy; tenuous; spiritlike; characterized by extreme delicacy, as form, manner, thought, etc.
4. (organic chemistry) To do with diethyl ether.
   an ethereal solution