any one of a great variety of unctuous combustible substances, 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.