In Buddhism: Naraka (hell). By extension, used figuratively for extreme suffering or a hellish place/situation.
仏教では悪業を積むと奈落に落ちると説かれる。
Buddhism teaches that those who commit evil deeds fall into Naraka.
彼は自分の過ちを悔いて、奈落を恐れていた。
He repented his mistakes and feared falling into hell.
小説では都会の闇を奈落になぞらえて描いている。
The novel depicts the city's darkness likened to a hell.
The very bottom; the end; a metaphorical lowest or worst possible state (as in 'the depths').
会社が倒産して、彼は生活の奈落の底に落ちた。
After the company went bankrupt, he fell into the depths of hardship.
失恋で奈落の底に落ちたような気分だった。
She felt as if she had fallen to the depths after the breakup.
負債の重さに押されて、家族は奈落に陥った。
Pressed by heavy debt, the family sank into ruin.
A trap room or the area beneath a theatre stage (the below-stage basement where stage machinery and trapdoors are located).
俳優は奈落から舞台に登場した。
The actor appeared on stage from the trap room beneath the stage.
舞台装置は奈落に隠されたワイヤーで動いている。
The stage machinery is operated by wires hidden in the trap room.