density
/ˈdensəti/ (bre, ipa) · /ˈdensəti/ (ame, ipa) · /ˈden(t)-sə-tē/ (ame, mw)
density — noun
1. a measurement that compares how many people, animals, or objects are present in
a measurement that compares how many people, animals, or objects are present in an area with the physical size of that area
Taipei has a much higher population density than most cities in eastern Taiwan.
population density — countable units per area
The housing density in this neighbourhood is low, with large yards between each house.
Amihan studied the density of wild deer across different forest regions for her biology report.
In Eri's city, the density of bus stops varies widely from one district to another.
Christopher checked the density of emergency exits in the building before his safety presentation.
- concentration
focuses on how much of something gathers in one spot; often used for resources or chemicals rather than populations
- compactness
emphasises how tightly things are packed together; less formal and rarely used for scientific measurements
- sparseness
describes an area with few people or objects spread far apart
用法筆記
Commonly combined with a noun describing what is being counted: population density, housing density, traffic density. The result is usually expressed as a number per square kilometre or per hectare.
常見錯誤
2. a scientific measurement of how much mass a material contains within a fixed amo
a scientific measurement of how much mass a material contains within a fixed amount of space, usually expressed as grams per cubic centimetre or kilograms per cubic metre
The density of water is about one gram per cubic centimetre at room temperature.
density of [substance] + measurement value
Gold's high density means a small bar can weigh several kilograms.
Elena compared the density of cooking oil with that of water for her science fair project.
Mathieu calculated the density of a small rock by weighing it and checking its volume in water.
The density of aluminium is about one-third that of steel, so aircraft use aluminium parts.
- specific gravity
compares a material's density to the density of water; used in older textbooks and some industries
- mass per unit volume
the full technical phrase; more precise but rarely used outside formal definitions
- buoyancy
not a true opposite; a less dense material floats in a denser one
用法筆記
In science classes, density is calculated using the formula density = mass ÷ volume. The standard SI unit is kg/m³, but g/cm³ is also common. Never use 'density' to mean simply 'heaviness' — a small piece of lead is heavy because of its high density, not because it has a lot of material overall.
常見錯誤
3. how packed, thick, or closely filled something is — for instance, the thickness
how packed, thick, or closely filled something is — for instance, the thickness of fog, the closeness of trees in a forest, or how many ideas fit into a short piece of writing
The density of the morning fog meant the airport had to delay all flights.
density of fog — natural phenomenon
Shirin noticed the density of the bamboo forest — she could barely see the sky.
The textbook's information density made it hard to read more than a few pages.
Valentina loved the density of the old fabric — it felt heavy and rich in her hands.
The density of the smoke made it hard for the firefighters to see inside the house.
- thinness
describes something that is not dense — thin fog, thin hair, thin forest cover
用法筆記
Unlike senses 1 and 2, this sense does not involve a precise numerical measurement. It describes a subjective impression of how densely something is packed. Distinguish from sense 1 (PEOPLE PER AREA): sense 3 can apply to fog, hair, vegetation, or writing — anything that can be described as 'dense' as a quality, not just a count per unit of area.