macrolideEnglishOxford New American Dictionarymacrolide /ˈmakrəˌlīd, ˈmækrəˌlaɪd / ▸ noun any of a class of antibiotics containing a lactone ring, of which the first and best known is erythromycin. – ORIGIN 1950s : from macro- + l(actone) + -ide.