Ether (Fischer-Z album) definition

(1) A colorless volatile highly inflammable liquid formerly used as an inhalation anesthetic

(2) A medium that was once supposed to fill all space and to support the propagation of electromagnetic waves

(3) Any of a class of organic compounds that have two hydrocarbon groups linked by an oxygen atom

(4) The fifth and highest element after air and earth and fire and water; was believed to be the substance composing all heavenly bodies