ylidPronunciation: /ˈɪlɪd/ (also ylide /ˈɪlʌɪd/)Definition of ylid noun Chemistry a compound having an uncharged molecule containing a negatively charged carbon atom directly bonded to a positively charged atom of sulphur, phosphorus, nitrogen, or another element: ammonium ylidsOrigin: 1950s: from -yl + -ideylid in other Oxford dictionaries Definition of ylid in the US English dictionary