According to Wikipedia: “The word aether, in Homeric Greek, means “pure, fresh air” or “clear sky”. In Greek mythology, it was thought to be the pure essence that the gods breathed, filling the space where they lived, analogous to the air breathed by mortals.”
However, in ancient and medieval sciences, aether (also spelled ether) is known as the material that fills the region of the universe above the terrestrial sphere. The concept of aether has been used in several theories to explain natural phenomena such as the traveling of light and gravity.
Also known as the “quintessence“, which is the Latin name of the fifth element used by alchemists as the medium similar/identical to that thought to make up the heavenly bodies. The term quintessence itself has become synonymous with elixirs, medicinal alchemy, as well as the philosopher’s stone.