density

American  

[den-si-tee] / ˈdɛn sɪ ti /

noun

densities plural

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. Electricity.

   1. 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.

   2. current density.

6. the degree of opacity of a substance, medium, etc., that transmits light.

7. Photography. 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 saved on a storage medium, as disk or tape, or displayed on an electronic screen.

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density British  

/ ˈdɛnsɪtɪ /

noun

1. the degree to which something is filled, crowded, or occupied

   high density of building in towns

2. obtuseness; stupidity

3.  ρ.  a measure of the compactness of a substance, expressed as its mass per unit volume. It is measured in kilograms per cubic metre or pounds per cubic foot See also relative density

4. a measure of a physical quantity per unit of length, area, or volume See charge density current density

5. physics photog See transmission density reflection density

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density Scientific  

/ dĕn′sĭ-tē /

1. A measure of the quantity of some physical property (usually mass) per unit length, area, or volume (usually volume).

2. ◆ Mass density is a measure of the mass of a substance per unit volume. Most substances (especially gases such as air) increase in density as their pressure is increases or as their temperature decreases.

3. ◆ Energy density is a measure of the amount of energy (often in the form of electromagnetic radiation) per unit volume in a region of space or some material.

4. See also Boyle's law

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density Cultural  

1. The relative heaviness of objects, measured in units of mass or weight per units of volume. (See specific gravity.)

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Other Word Forms

• nondensity
  noun
• superdensity
  noun

Etymology

Origin of density

First recorded in 1595–1605; from Latin dēnsitās, equivalent to dēns(us) dense + -itās -ity

Explanation

Density describes how compact or concentrated something is. For example, suppose you have two boxes, one large and one small. However, they both weigh the same. That means the small box has a higher density than the large box. Density also tells how concentrated or crowded something is. You may have heard of population density. In a city, there are many people packed into a small area, giving it a high population density. In a rural area, there are more fields or wooded areas between houses. That means there are fewer people living in a larger area, which is why it has a low population density.

Example Sentences

The design enables higher power and torque density.

From Barron's • May 20, 2026

Empower’s technology enables power density, speed and efficiency.

From The Wall Street Journal • May 19, 2026

“Southern California has a high population density with a high electricity demand, which is projected to continue growing substantially,” said Patricia Hidalgo-Gonzalez, director of the Renewable Energy and Advanced Mathematics lab at UC San Diego.

From Los Angeles Times • May 17, 2026

The team used instruments anchored to the seafloor that continuously measure pressure, temperature, density, and ocean currents.

From Science Daily • May 10, 2026

Anything or anyone who falls through the event horizon will soon reach the region of infinite density and the end of time.

From "A Brief History of Time: And Other Essays" by Stephen Hawking

Related Words

• frequency
• quantity
• thickness