E*the"re*al (?), 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.

Go, heavenly guest, ethereal messenger.

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

Vast chain of being, which from God began,
Natures ethereal, human, angel, man.

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

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 Ĺ“nanthic ether). -- Ethereal salt (Chem.), a salt of some organic radical as a base; an ester.