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