Average population per unit area; especially, the average number of people who live on each square kilometer (or square mile) of land.

(statistics) The mean (usually arithmetic, but possibly geometric) of all members of a population or all possible values from which a sample can be taken, as opposed to a sample mean.

(physics) The creation of a system in which more atoms or molecules are in an excited state than in a ground state.

plural of general population

The general public. / The main body of inmates in a prison, excluding those being detained in solitary confinement, protective custody, a medical wing or on death row.

A population that is inferred to have existed based on data that has been reconstructed rather than on direct sampling.

plural of ghost population

A graphical illustration of the distribution of a population (typically that of a country or region of the world) by age groups and sex; it typically forms the shape of a pyramid when the population is growing.

plural of population pyramid

(law) A process in which the major political parties compete with each other to be tough on crime.