diethylene glycolPronunciation: /dʌɪˈɛθɪliːn, -θ(ə)l-/Definition of diethylene glycol noun [mass noun] Chemistry a colourless soluble liquid used as a solvent and antifreeze. Chemical formula: (C2H4OH)2O diethylene glycol in other Oxford dictionaries Definition of diethylene glycol in the US English dictionary