Definitionen
1.NounMatter which cannot be detected by its radiation but whose presence is inferred from gravitational effects.
2.NounMatter which has mass but which does not readily interact with normal matter except through gravitational effects.
3.NounUnclassified or poorly understood genetic material.
4.Noun↑ Henri Poincaré, La Voie lactée et la théorie des gaz, Bulletin de la Société astronomique de France 20, 1906, 153–165.
5.Noun↑ Robert J. Trumpler, Dark Nebulae, Leaflet 44, July 1932, Astronomical Society of the Pacific, 179–182.