specific gravity

American  

[spi-sif-ik grav-i-tee] / spɪˈsɪf ɪk ˈgræv ɪ ti /

noun

Physics.

1. the ratio of the density of any substance to the density of some other substance taken as standard, water being the standard for liquids and solids, and hydrogen or air being the standard for gases.

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specific gravity British  

noun

1. the ratio of the density of a substance to that of water See relative density

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specific gravity Scientific  

/ spĭ-sĭf′ĭk /

1. 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.

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specific gravity Cultural  

1. 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.

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Etymology

Origin of specific gravity

First recorded in 1660–70; the variant relative density was first recorded in 1875–80

Example Sentences

The device uses optical sensors to work out your "urine specific gravity" – a measure of urine's density compared to clean water.

From BBC • Jun. 22, 2026

Their specific gravity allows them to sink and walk or run along the bottom of rivers and lakes.

From Salon • Mar. 22, 2024

In the case of this table, specific gravity is the ratio of density of a substance to the density of pure water at the same conditions.

From Textbooks • Feb. 14, 2019

Here, Russian missiles had a distinct advantage, as their lower specific gravity allowed them to float vertically, like an ocean buoy.

From Washington Post • Dec. 27, 2017

Grief, terror, love, longing — these were intangibles, but the intangibles had their own mass and specific gravity, they had tangible weight.

From "The Things They Carried" by Tim O'Brien