Originally posted by Enlightened E Gremlin:

Its basically Aether...which is what everything is made up of in the real world. This originates from Ancient Meta Physics.

Actually that's twice wrong. Originally aether refers to the heavens, basically everything in our universe that's not another element like earth, water and fire. It's the sky essentially, it's light, space, air pressure etc.

Eitr on the other hand comes from the concept of primordial ooze and poison. It's the origin of the jotnar and snakes/dragons. It's a manifestation of primordial matter of Ginnungagap where fire and ice meet. It's the origin of matter from which the world is later made.

It's strongly linked to the concept of fertile soil which to the Norse meant soil filled with rainworms. Worms and snakes were the same thing to them, beings directly born from fertile primal matter. But like all good things, to much will kill you.

Etymologically this has no connection with Aether. The element of Earth is linked to Eitr while it's borderline the opposite of aether.