1 [U] the number of things or people in a place in relation to its area 密度（某地方的物或人的数目与该地方面积的关系）: There is a high density of wildlife in this area. 这地区的野生生物密度很高。

2 [C,U] (technical术语) the relation of the weight of a substance to its size 密度（某物质的重量与所占空间的关系）: Lead has a high density. 铅的密度很高。