lanolin, greasy, yellow substance extracted from wool. When purified, it is used as a base for ointments and creams, as a lubricant, and in finishing and preserving leather. It is also a constituent of some varnishes and paints. Chemically, lanolin is chiefly a mixture of cholesterol and the esters of several fatty acids. With water it forms an emulsion. As a waste product in wool processing, it is known also as wool wax, wool fat, or wool grease.