lipopolysaccharidePronunciation: /ˌlɪpəʊpɒlɪˈsakərʌɪd, ˌlʌɪ-/Definition of lipopolysaccharide noun Biochemistry a complex molecule containing both lipid and polysaccharide parts. lipopolysaccharide in other Oxford dictionaries Definition of lipopolysaccharide in the US English dictionary