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 醚；乙醚 - the ether(old use or literary)
the upper part of the sky 苍穹；苍天；太空 - the ether
the air, when it is thought of as the place in which radio or electronic communication takes place 以太 The messages simply vanish into the ether after 24 hours. 这些信息在24小时后就消失在空气中了。
Word Originlate 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.