"act of making dark or obscure; fact of being overclouded," c. 1600, noun of action from obnubilate (v.).
"dark-skinned Jewish tribe of Abyssinia," 1710, from Ethiopian, literally "exiled, wanderer, immigrant," from falasa "he wandered."
1760 "gloomy, shadowy" (earlier sombrous, c. 1730), from French sombre "dark, gloomy," from Old French sombre (14c.), from an adjective from Late Latin subumbrare "to shadow," from sub "under" (see sub-) + umbra "shade, shadow" (perhaps from a suffixed form of PIE *andho- "blind, dark;" see umbrage). Related: Somberly; somberness.
early 15c., opake, "dark, shaded, unlit" (a sense now obsolete), from Latin opacus "shaded, in the shade, shady, dark, darkened, obscure," of unknown origin. Spelling influenced after c. 1650 by French opaque (c. 1500), from the Latin. Meaning "impervious to the rays of light" is from 1640s. Figurative sense of "obscure, hard to understand" is from 1761. Related: Opaquely; opaqueness.
The term "Hornblende" is an old German name for any dark, prismatic crystal found with metallic ores but containing no valuable metal (the word "Blende" indicates "a deceiver") [Herbert Bucksch, "Dictionary Geotechnical Engineering," 1995]
celebrated Greek physician of 2c.; his work still was a foundation of medicine in the Middle Ages and his name is used figuratively for doctors.
1550s, "somewhat dark, not luminous, dim;" see dusk + -y (2). "The normal source of an adj. in -y is a sb.; but the substantival use of dusk is not known so early as the appearance of dusky, so that the latter would appear to be one of the rare instances of a secondary adj. ..." [OED]. Meaning "rather black, dark-colored" is from 1570s. Related: Duskily; duskiness.
1827 as the years of someone's life between ages 80 and 89; from 1833 as the ninth decade of years in a given century; from 1854 with reference to Fahrenheit temperature. See eighty.