To die; to cease living; to pass away.
おばあさんは昨夜静かに死んだ。
My grandmother quietly passed away last night.
もしこの薬が効かなければ、命に関わる危険で死ぬこともあり得る。
If this medicine doesn't work, there is a risk to life and one could die.
魚は水がなくなるとすぐ死ぬ。
Fish die quickly without water.
To lose spirit or vigor; to appear lifeless (colloquial usage, e.g., 'his eyes looked dead').
長時間の残業で彼は元気が死んでいるようだった。
After long hours of overtime he looked completely drained.
その知らせを聞いて、部屋の雰囲気が一瞬で死んだ。
When they heard the news, the atmosphere in the room instantly died.
To cease or stop functioning; to die off (used for machines, batteries, sounds, etc.).
スマホのバッテリーが切れて、急に電源が死んだ。
The phone's battery died and the power suddenly went off.
音楽がフェードアウトして最後に音が死んだ。
The music faded out and finally the sound died away.