cosmology A hypothetical form of matter that is believed to make up 90 percent of the universe; it is invisible (does not absorb or emit light) and does not collide with atomic particles but exerts gravitational force.

Roget 421: darkness etc. adj., absence of light; blackness etc. (dark color) 431; obscurity, gloom, murk; dusk etc. (dimness) 422.    Cimmerian darkness^†, Stygian darkness, Egyptian darkness; night; midnight; dead of night, witching hour of night, witching time of night; blind man's holiday; darkness visible, darkness that can be felt; palpable obscure; Erebus [Lat.]; the jaws of darkness" [Midsummer Night's Dream]; sablevested night" [Milton]. shade, shadow, umbra, penumbra; sciagraphy^†.    obscuration; occultation, adumbration, obumbration^†; obtenebration^†, offuscation^†, caligation^†; extinction; eclipse, total eclipse; gathering of the clouds.    shading; distribution of shade; chiaroscuro etc. (light) 420.    noctivagation^†.    [perfectly black objects] black body; hohlraum [Phys.]; black hole; dark star; dark matter, cold dark matter.    ... show more

Dutch: donkere materie
Polish: ciemna materia