Translation guide
The English word "density" can refer to physical compactness, concentration of things in an area, or abstract intensity. In Japanese, different words and patterns are used depending on what is dense and the context.
Expressing how compact or heavy a material is per unit volume (e.g., density of metal, liquid, gas).
The standard scientific and everyday term for physical density. Used for solids, liquids, gases, and abstract concepts like population density.
鉄の密度はアルミニウムより高い。
The density of iron is higher than that of aluminum.
この液体の密度を測ってください。
Please measure the density of this liquid.
Specific gravity; often used in technical contexts to compare density to water. Can also be used metaphorically for importance or weight.
この金属の比重は約8です。
The specific gravity of this metal is about 8.
Describing how crowded or packed something is, like people, trees, or houses.
Used for population density, housing density, etc. Often combined with words like 人口 (population) or 住宅 (housing).
東京は人口密度が非常に高い。
Tokyo has a very high population density.
この地域は住宅密度が低い。
This area has a low housing density.
Degree of crowding or clustering; emphasizes the state of being packed together. Often used for buildings or objects.
都市の密集度が問題になっている。
The density of urban crowding has become a problem.
Describes something as being densely packed or crowded. More descriptive than using a noun.
この辺りは家が密集している。
Houses are densely packed around here.
Expressing how much of something non-physical is packed into a space or time, like data density, energy density, or density of content.
Also used for abstract density. Common in phrases like 情報密度 (information density) or エネルギー密度 (energy density).
この文章は情報密度が高い。
This text has a high information density.
バッテリーのエネルギー密度を向上させる。
Improve the energy density of the battery.
Literally 'thick' or 'dense', used for abstract things like content, flavor, or color. Implies richness or intensity.
この小説は内容が濃い。
This novel is dense with content.
密度 (みつど) is the general term for density (mass per volume). 比重 (ひじゅう) specifically means specific gravity, comparing density to water. In everyday contexts, 密度 is more common.
密度 is often used in compound nouns like 人口密度 (population density) or 情報密度 (information density). To say something is dense, you can use 密度が高い (high density) or 密度が低い (low density).