(lipide). An inclusive term for fats and fat-derived materials. It includes all substances which are (1) relatively insoluble in water but soluble in organic solvents (benzene, chloroform, acetone, ether, etc.); (2) related either actually or potentially to fatty acid esters, fatty alcohols, sterols, waxes, etc.; and (3) utilizable by the animal organism. One of the chief structural components of living cells.See Phospholipid; Fat; Fatty Acid.