Medical Definition of ethylene
1: a colorless flammable gaseous unsaturated hydrocarbon C2H4 that is found in coal gas, can be produced by pyrolysis of petroleum hydrocarbons, is used in medicine as a general inhalation anesthetic, and occurs in plants functioning especially as a natural growth regulator that promotes the ripening of fruit—called also ethene
2: a divalent hydrocarbon group C2H4 derived from ethane
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