phospholipid /ˌfɑs.foʊˈlɪ.pɪd/ noun1 •Any lipid, such as lecithin or cephalin, consisting of a diglyceride combined with a phosphate group and a simple organic molecule such as choline or ethanolamine; they are important constituents of biological membranes.An index of the amount of phospholipids present was secured from the total phosphorus content of a third aliquot, the method employed being the colorimetric procedure devised by Whitehorn. — 1926 formsphospholipids