| 1. greasy liquid (derived from animal, vegetable, and mineral substances) that does not mix with water and is used for many purposes (i.e. food, fuel, lubrication, etc.); petroleum. spread with oil; grease, lubricate. oilengines, using either an atomized spray or the vapor (produced by heat) of a comparatively heavy oil, as petroleum or kerosene. in all of these the gas is mixed with a definite amount of air, the charge is composed in the cylinder and is then exploded either by a flame of gas (..see: internal-combustion engine |