In the late 19th century, luminiferous aether (or ether), meaning light-bearing aether, was the term used to describe a medium for the propagation of light. The word aether stems via Latin from the Greek αιθήρ, from a root meaning to kindle, burn, or shine. It signified the substance thought in ancient times to fill the upper regions of space, beyond the clouds.
Later theories including special relativity were formulated without the concept of aether. Today the aether is regarded as a superseded scientific theory.
Reference:
http://en.wikipedia.org/wiki/Lumiferous_aether
