暗 （アン） darkness

暗雲 （アンウン） dark clouds, threatening signs, ominous indications

明暗 （メイアン） light and darkness, light and shade

冥暗 （メイアン） gloom, shade

暗い （くらい） dark, gloomy, murky, depressed, dispirited, down in the dumps, dark (mood), dark (in colour), dull, ill-boding, dark (e.g. past), suspicious, unlikely (to succeed), hopeless, unpromising, unfamiliar (with), ignorant (of)

暗い過去 （くらいかこ） shadowy past, murky past

眩む （くらむ） to be dazzled by, to be dizzied by, to be disoriented by, to be lost in (greed, lust, etc.), to become dark

暮れる （くれる） to get dark, to grow dark, to end (of a day, year, season, etc.), to come to an end, to close, to be sunk in (e.g. despair), to be lost in (e.g. thought), to be overcome with