Sudden Death
noun, verbal noun
A sudden death makes for just that, a sudden death.
きゅうし
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.
父が急死した時、私は高校生でした。
I was a high school student when my dad suddenly passed away.
マルちゃんのところのおじいさん、モチがノドにつまって急死だったんだって。
Apparently, the old man at Maru-chan's place died suddenly when a sticky rice cake got stuck in his throat.
彼とはよくケンカになっちゃって、それが本当にイヤだったんだけど、今ではケンカもできなくなっちゃってすっごく悲しいよ。まさか急死しちゃうなんて思ってもみなかったからさ。
I often argued with my boyfriend and I hated it, but I even miss the arguments now. I never expected that he would drop dead.