I got it. It could be that its the original meaning: Aether (mythology), the personification of the "upper sky", space and heaven, in Greek mythology.
Or the Science, engineering, and philosophy version of aether:
The Aether of classical elements is a concept, historically, used in science (as a medium) and in philosophy (as a substance).
Any number of Aether theories in alchemy, natural philosophy, and modern physics which suppose a "fifth element".
Luminiferous aether, in early physics considered to be the medium through which light propagates, proved false.
Ether, a class of chemical compounds, or specifically:
Diethyl ether, which has the common name "ether".
Comptia which is it?