manku -man- gismu

x₁ is dark/lacking in illumination.

(cf. blabi, gusni, ctino; use kandi or xekri with colors, ctino)

In notes:

blabi: x₁ is white/very-light colored [color adjective].
ctino: x₁ is a shadow/the shade of object x₂, made by light/energy source x₃.
gusni: x₁ [energy] is light/illumination illuminating x₂ from light source x₃.
kandi: x₁ is dim/dull/pale/non-intense in property x₂ (ka) as received/measured by observer x₃.
xekri: x₁ is black/extremely dark-colored [color adjective].
manze'a: z₁ becomes darker/darkens by amount z₃.
mardurudra: x₁ is a specific kind of bad weather characterized by large dark rain clouds that block out most of the daylight, large, cold rain drops and an overall dark, uncomfortable and unsettling atmosphere, optionally accompanied by icy wind, such that a change in the weather conditions would be a relief to anyone present, both physically and emotionally.