Metaphysics and mythology
aether (classical element), the material supposed to fill the region of the universe above the terrestrial sphere
Aether (mythology) was the personification of the "upper sky", space and heaven, in Greek mythology
Science and engineering
aether theories in alchemy, natural philosophy, and early modern physics that suppose a "fifth element"
luminiferous aether, in late nineteenth century physics considered to be the medium through which light propagates
ether, a class of chemical compounds, or specifically: diethyl ether, which has the common name "ether"
