tenebrous
Dark and gloomy; obscure.
figuratively, literary
Met in a dusky arch,[…]
Over their heads the towering and tenebrous boughs of the cypress
Where it comes from
] From Middle English tenebrose, from Anglo-Norman tenebrous (earlier tenebrus), from Latin tenebrōsus, itself from tenebrae (“darkness, shadows”).
Adapted from the Wiktionary entry tenebrous (CC BY-SA 4.0).