/ ˈiːθə(r); NAmE / noun [ U ]
1.
a clear liquid made from alcohol, used in industry as a solvent and, in the past, in medicine to make people unconscious before an operation
2.
the ether ( old use or literary ) the upper part of the sky :
Her words disappeared into the ether.
3.
the ether the air, when it is thought of as the place in which radio or electronic communication takes place
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WORD ORIGIN
late Middle English : from Old French , or via Latin from Greek aithēr upper air, from the base of aithein burn, shine. Originally the word denoted a substance believed to occupy space beyond the sphere of the moon. Sense 1 arose in the mid 18th cent.