Calque of GermanDunkle Materie, from dunkel(“dark”) and Materie(“matter”). Coined by Swiss astronomer Fritz Zwicky in German in 1933, to account for the apparent mass needed to account for galaxy clusters, where the mass of luminous matter did not add up to enough of a gravitational effect, inferring nonluminous matter must exist to account for the missing mass. The term gained new popularity due to the missing mass found in galaxies to account for galaxy rotation curves discovered by Vera Rubin in research published in English in the 1970s.
2001, Susan M. Fitzpatrick, John T. Brue, Carving Our Destiny: Scientific Research Faces a New Millennium[1]:
The evidence for dark matter in galaxies started to accumulate in the mid-1970s. By the following decade it became clear that essentially all galaxies, including our own Milky Way, are surrounded by extensive halos of dark matter.
2004, L. Bergström, A. Goobar, “Particle Astrophysics and the Dark Sector of the Universe”, in John W. Mason, editor, Astrophysics Update, pages 124–125:
On large scales like that of clusters of galaxies, gravitational lensing indicates that the dark matter is smoothly distributed, on the average.