over-densityn.
/ˌəʊvəˈdɛnsᵻti/, U.S. /ˌoʊvərˈdɛnsədi/ 1. Excessive or undesirable density (esp. of population).
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1852 Jrnl. Statist. Soc. 15 242 In India..the population, probably from over-density, would seem, from the most reliable accounts, to have diminished during the last half century.
1944 L. Fraser Germany between Two Wars vi. 153 It was no longer a claim for relief from the burden of an existing over-density of population; it was rather a warning that Germany intended to elbow herself into a more dominant position among the world's Great Powers.
1974 G. Abraham in M. Cooper Mod. Age ii. 105 His melodic lines and harmony are free from hyper-chromaticism, his textures from over-density and his rhythms from flaccidity.
2002 Independent (Nexis) 3 Sept. Over density of population and unclean habits are helping spread of these diseases in an epidemic form.
2. Astronomy. Greater density in a region of space than the average; a region so characterized, esp. as favouring star formation.
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the world > the universe > star > star-matter > [noun] > space density
space density1923
over-density1979
1979 Astrophysical Jrnl. 232 678/2 There are of course, regions of overdensity which do not collapse to black holes.
1994 N.Y. Times (Nexis) 29 Nov. c1 The computer model..assumes the existence of unseen cold dark matter and random overdensities acting as seeds.
2001 Washington Post (Nexis) 30 Apr. a1 These ripples signal the tiny peaks and valleys of over-density and under-density, which gravity gradually has built into the universe we see today.
This is a new entry (OED Third Edition, December 2004; most recently modified version published online March 2022).
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n.1852