aether

n. (Physics) theoretical medium of great elasticity and extreme thinness of consistency supposed to fill all unoccupied space and transmit light and heat

The term aether, æther or ether may refer to one of the following.The original meaning: Aether (mythology), the personification of the "upper sky", space and heaven, in Greek mythology.
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Noun
1. personification of the sky or upper air breathed by the Olympians; son of Erebus and Night or of Chaos and Darkness
(hypernym) Greek deity

Noun
1. a medium that was once supposed to fill all space and to support the propagation of electromagnetic waves
(synonym) ether
(hypernym) medium

n. ether, colorless liquid used as a solvent and formerly as an anesthetic (Chemistry)

(n.)
See Ether.