The ratio of the mass of a solid or liquid to the mass of an equal volume of distilled water at 4°C (39°F) or of a gas to an equal volume of air or hydrogen under prescribed conditions of temperature and pressure.
The relative density of a solid or liquid, usually when measured at a temperature of 20°C, compared with the maximum density of water (at 4°C). For example, the specific gravity of carbon steel is 7.8, that of lead is 11.34, and that of pure gold is 19.32.
The mass of a substance, given as a multiple of the mass of the same volume of a standard substance (usually water). The specific gravity of aluminum is 2.70; hence, a cubic foot of aluminum weighs 2.70 times as much as a cubic foot of water.