Using the broadest possible definition, a lipid (Greek lipos = fat ) may be defined as a compound of low or intermediate molecular weight (5000), a substantial proportion of which is made up of hydrocarbons. Included are diverse compounds such as fatty acids; soaps; detergents; steroids; mono-, di-, and triacylglycerols; and more complex compounds such as phospholipids, sphingolipids, glycolipids, and lipopolysaccharides.