重体(じゅうたい)seriously ill, serious condition, critical state

重体(じゅうたい)の人(ひと)を病院(びょういん)で治療(ちりょう)する。

They treat a seriously ill person in the hospital.

交通(こうつう)事故(じこ)に遭(あ)って重体(じゅうたい)に陥(おちい)りました。

I was involved in a traffic accident and fell into a critical state.

重体(じゅうたい)とは生命(せいめい)に危機(きき)がある状態(じょうたい)のことです。

'Critical condition' refers to a state where one's life is at risk.

トラックに跳(は)ねられたら重体(じゅうたい)に陥(おちい)るのも当然(とうぜん)です。

It's only natural that you'd be in a critical condition if you were hit by a truck.

ニュースによると刃物(はもの)で刺(さ)されて重体(じゅうたい)だった人(ひと)に意識(いしき)が戻(もど)ったとか。

According to the news, it seems that the person who was in critical condition after being stabbed with a knife has regained consciousness.