density
noun [ C or U ] uk/ˈden.sɪ.ti/ us/ˈden.sə.t̬i/
(THICKNESS)
C1 (also denseness)（人口等的）密度
the number of people or things in a place when compared with the size of the place
The area has a high/low population density. 该地区人口密度大／小。
We were unable to move because of the density of the crowd. 人太多，我们根本就动不了。
(OF MATTER)
physics specialized（物质的）密度
the relationship between the mass of a substance and its size
Lead has a high density. 铅的密度大。
Aluminium is low in density. 铝的密度小。