Cimmerian
Etymology
From the Cimmerians, a people Homer’s "Odyssey" places at the edge of the world, "shrouded in mist and cloud," where the sun never shines. Whatever the real nomadic Cimmerians of history were like, it is this mythic land of endless night that gave the adjective its meaning of profound, oppressive darkness.
adjective · /sih-MEER-ee-un/
Very dark and gloomy, as if in perpetual shadow.
What it names
Deep, unrelieved darkness — use it for a murk so total it feels like a place the sun never reaches, literally or in mood.
Example
The power cut plunged the stairwell into cimmerian black, and we felt our way down by the handrail.
Related idea
Tenebrous means shadowy and dark in a general way; cimmerian intensifies it to a mythic extreme — darkness so complete it suggests a world without daylight at all.
See also