/den"si tee/, n., pl. densities.1. the state or quality of being dense; compactness; closely set or crowded condition.2. stupidity; slow-wittedness; obtuseness.3. the number of inhabitants, dwellings, or the like, per unit area: The commissioner noted that the population density of certain city blocks had fallen dramatically.4. Physics. mass per unit volume.5. Elect.a. the quantity of electricity per unit of volume at a point in space, or the quantity per unit of area at a point on a surface.b. See current density.6. the degree of opacity of a substance, medium, etc., that transmits light.7. Photog. the relative degree of opacity of an area of a negative or transparency, often expressed logarithmically.8. Computers. a measure of the compactness of data stored on an external storage medium, as disk or tape, or displayed on a CRT or other screen.[1595-1605; < L densitas, equiv. to dens(us) DENSE + -itas -ITY]
* * *IMass of a unit volume of a material substance.It is calculated by dividing an object's mass by its volume. In the International System of Units, and depending on the units of measurement used, density can be expressed in grams per cubic centimetre (g/cm3) or kilograms per cubic metre (kg/m3). The expression "particle density" refers to the number of particles per unit volume, not to the density of a single particle. See also specific gravity.II(as used in expressions)
* * *▪ chemistry and physicsmass of a unit volume of a material substance, expressed as kilograms per cubic metre in MKS or SI units; the densities of common solids, liquids, and gases are listed in textbooks and handbooks. Density offers a convenient means of obtaining the mass of a body from its volume or vice versa; the mass is equal to the volume multiplied by the density, while the volume is equal to the mass divided by the density. The weight of a body, which is usually of more practical interest than its mass, can be obtained by multiplying the mass by the acceleration of gravity. Tables that list the weight per unit volume of substances are also available; this quantity has various titles, such as weight density, specific weight, or unit weight. See also specific gravity. The expression particle density refers to the number of particles per unit volume, not to the density of a single particle.
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