n 1  :  a medium that in the wave theory of light permeates all space and transmits transverse waves  2 a  :  a light volatile flammable liquid C₄H₁₀O used esp. formerly chiefly as an anesthetic - called also diethyl ether , ethyl ether , ethyl oxide   b  :  any of various organic compounds characterized by an oxygen atom attached to two carbon atoms .
 
 
 
Similar sounding terms:  Eu·the·ria 
 
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