tenebricose
Full of darkness; gloomy, tenebrous.
rare
Tene′bricose. […] Dark; gloomy.
Where it comes from
Learned borrowing from Latin tenebricōsus (“full of darkness or gloom”), from tenebricus (“dark, gloomy”) + -ose (“full of”).
Adapted from the Wiktionary entry tenebricose (CC BY-SA 4.0).