RhymeZone: ether definitions

Definitions of ether:

noun: a colorless volatile highly inflammable liquid formerly used as an inhalation anesthetic
noun: a medium that was once supposed to fill all space and to support the propagation of electromagnetic waves
noun: any of a class of organic compounds that have two hydrocarbon groups linked by an oxygen atom
noun: the fifth and highest element after air and earth and fire and water; was believed to be the substance composing all heavenly bodies