The way I understand the word "density" to be used is as if a space is filled by infinitesimally small objects--points. However, in my usage, I'm looking for a word that signifies that a certain percentage of space is occupied by objects.
To illustrate, consider a space of a given volume, containing a given number of spheres. Compare this with a space that has twice the volume and contains the same number of spheres but each now also has twice the volume. "Density", as the number of objects per unit of volume, is now half. But "occupancy", as the fraction of space occupied by the spheres, is the same in both cases.
What is a good word for this "occupancy" measure?