tenebrous
[adjective]
Synonyms: dark, caliginous, dim, dusk, dusky, gloomy, lightless, murky, obscure, unilluminated, ambiguous, amphibological, equivocal, sibylline, uncertain, unclear, unexplicit, unintelligible, vague

[TahlilGaran] English Synonym Dictionary ▲

tenebrous adjective. ['tɛnɪbrǝs] Chiefly literary. LME.
[Old French tenebrus (mod. ténébreux) from Latin tenebrosus TENEBROSE: see -OUS.]
Full of darkness, dark; fig. obscure, gloomy.
■ J. Buchan Everything was drained of colour and frozen into a tenebrous monotony.
■ S. Heaney Aside from their tenebrous conversation, I sat learning my catechism.

■ tenebrousness noun (rare) darkness E18.

[TahlilGaran] English Dictionary ▲