Panmixia is the free interbreeding of individuals of a population with each other.
It is the ability of individuals in a population to interbreed without restriction; individuals are able to move freely within their habitat, perhaps hundreds to thousands of miles, and thus interbreed with other members of the population.
A panmictic population is a population in which all individuals are potential mates. This implies that there are no mating constraints in the population, neither genetic nor behavioral, and that therefore any recombination is possible.
In genetics, random mating refers to the mating of individuals regardless of any physical, genetic, or social preferences. In other words, mating between two organisms is not influenced by any environmental, hereditary, or social interaction. Consequently, potential mates have an equal chance of being selected.