1Darkness - the absence of light, as at night or in a dark place.
停電で部屋が闇に包まれた。
The power went out and the room was enveloped in darkness.
深い山の中は、夜になると完全な闇になる。
Deep in the mountains, it becomes completely dark at night.
闇の中に目を凝らすと、かすかに人影が見えた。
When I strained my eyes in the darkness, I could faintly make out a figure.
2A figurative darkness - a state of despair or hopelessness, feeling lost with no way forward.
事業に失敗し、彼は深い闇の中にいた。
After his business failed, he was in deep despair.
大切な人を失って、心に闇が広がった。
After losing someone dear to him, a darkness spread through his heart.
3Something hidden or kept secret, out of public view, as in 闇に葬る (to bury in secrecy).
事件の真相は闇に葬られたままだ。
The truth of the incident remains buried in secrecy.
その取引には多くの闇が隠されているようだ。
It seems that deal has a lot of hidden secrets behind it.
4Illicit or illegal transactions and distribution channels - the black market.
近年、SNSで闇バイトを募集する事件が問題になっている。
In recent years, cases of recruiting people for illicit 「dark part-time jobs」 via social media have become a serious problem.
違法な薬物が闇市場で取引されていた。
Illegal drugs were being traded on the black market.
闇金融からお金を借りて、余計に苦しい状況になった。
Borrowing money from illegal lenders only made his situation worse.