Information density, the amount of information compared to many units

Density, mass per volume

In forcing (mathematics), a subset D of a forcing notion (P, ≤ ) is called dense in P if for any p in P there is d in D with d≤p

Specific gravity, a dimensionless ratio based on the density of a substance to the density of water

Relative density, a measure of density in comparison to the density of something else

Probability density function, a function which maps probabilities across the real line and whose integral is 1

Energy density, potential energy per unit volume or mass, depending on context

Spiritual density, states of being for various planes of existence

Computer storage density, bits (how computers store information) over an amount of area or volume

Schnirelmann density in number theory

Population density, population per unit area

Density estimation is the construction of an estimate of a probability density function

Charge density, the electric charge per volume

Kernel density estimation, used in statistics to estimate a probability density function of a random variable

Density in graph theory, the fraction of possible edges that exist in a graph

Current density, the ratio of electric current to area

Lebesgue density in measure theory

Optical density, the absorbance of an element

Vapour density, a relative density used for gases

Planck density, Planck mass per Planck length

Tensor density in differential geometry

Dense-in-itself, in geometry, is a set that contains no isolated points

Linear density, mass over a (one-dimensional) line

Area density, mass over a (two-dimensional) area

Force density, force per unit volume

Dense order in order theory

Dense set and nowhere dense set in topology

Natural density (also called asymptotic density) in number theory