1. 密度;稠密;密集
    Density is the extent to which something is filled or covered with people or things.

    e.g. ...a law which restricts the density of housing...
           限制房屋密集程度的法规
    e.g. The region has a very high population density.
           该地区的人口密度很高。

2. （物质或物体的）密度
    In science, the density of a substance or object is the relation of its mass or weight to its volume.

density的反义词

    e.g. Jupiter's moon Io, whose density is 3.5 grams per cubic centimetre, is all rock.
           密度为每立方厘米 3.5 克的木星卫星木卫一上遍布岩石。