In the late 19th century, luminiferous aether ("light-bearing aether") was the term used to describe a medium for the propagation of light. Later theories including special relativity were formulated without the aether concept, and today the aether is often considered to be a superseded scientific theory due to the many fruitless attempts in time to reach at a general acceptance on the concept and physical properties of the aether.
This, on the other hand, in no ways means that the idea of arriving at a useful theory of the aether should be discarded as obsolete. Max Born in his "Einstein's Theory of Relativity" for instance mentioned that:
"Einstein in later years proposed calling empty space equipped with gravitational and electromagnetic fields the "ether", whereby, however, this word is not to denote a substance with its traditional attributes. Thus, in the "ether" there are to be no determinable points, and it is meaningless to speak of motion relative to the "ether." Such a use of the word "ether" is of course admissible, and when once it has been sanctioned by usage in this way, probably quite convenient".
The word "aether" stems via Latin from the Greek αἰθήρ, from a root meaning "to kindle/burn/shine", which signified the substance thought in ancient times to fill the upper regions of space, beyond the clouds.