lip·o·pol·y·sac·cha·ride (l?p??-p?l??-s?k??-r?d?, l??p?-)n. Any of a group of polysaccharides in which a lipid constitutes a portion of the molecule, found in the outer cell wall of gram-negative bacteria.American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.lip?o?pol?y?sac?cha?ride (?la?p o??p?l i?sæk ??ra?d, -r?d, ?la? po?-) n. any of a class of polysaccharides to which lipids are attached. [1950?55] Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.