Any one of a great variety of unctuous combustible substances, more viscous than and not miscible with water; as, olive oil, whale oil, rock oil, etc. They are of animal, vegetable, or mineral origin and of varied composition, and they are variously used for food, for solvents, for anointing, lubrication, illumination, etc. By extension, any substance of an oily consistency; as, oil of vitriol.
To smear or rub over with oil; to lubricate with oil; to anoint with oil.
Any of a variety of oily or greasy organic compounds found as major structural components of living cells; they are insoluble in water but soluble in organic solvents such as alcohol and ether, and include the common fats, cholesterol and other steroids, phospholipids, sphingolipids, waxes, and fatty acids; some of the lipids, together with proteins and carbohydrates, form an essential structural component of living cells, as in the cell walls and membranes. The term lipid refers to its solubility in nonpolar solvents, and has no significance with regard to chemical structure.
