[den.si.ty] n, pl -ties (1603) 1: the quality or state of being dense
2: the quantity per unit volume, unit area, or unit length: as a: the mass of a substance per unit volume b: the distribution of a quantity (as mass, electricity, or energy) per unit usu. of space (as length, area, or volume) c: the average number of individuals or units per space unit "a population ~ of 500 per square mile" "a housing ~ of
10. houses per acre" 3 a: the degree of opacity of a translucent medium b: the common logarithm of the opacity