Hypothetical class of dark-matter candidates made up of slow-moving subatomic particles, such as supersymmetric relics of a very early stage of the Big Bang.

a type of dark matter that was moving at much less than the speed of light 10,000 years after the Big Bang. (see dark matter)

Cold dark matter (or CDM) is a refinement of the big bang theory that contains the additional assumption that most of the matter in the Universe consists of material which cannot be observed by its electromagnetic radiation and hence is dark while at the same time the particles making up this matter are slowly moving and hence are cold. As of 2006, most cosmologists favor the cold dark matter theory as a description of how the universe went from a smooth initial state at early times (as shown by the cosmic microwave background radiation), to the lumpy distribution of galaxies and their clusters we see today — the large-scale structure of the universe.