(Science: biochemistry) long chain amino alcohol that bears an approximate similarity to glycerol with a hydrophobic chain attached to the 3 carbon. Forms the class of sphingolipids when it carries an acyl group joined by an amide link to the nitrogen. Forms sphingomyelin when phosphoryl choline is attached to the 1 hydroxyl group. Gives rise to the cerebroside and ganglioside classes of glycolipids when oligosaccharides are attached to the 1 hydroxyl group. Not found in the free form.