na-adjective, noun
Primarily used in medical or formal contexts to describe a life-threatening or very serious condition. Often appears in phrases like 重篤な状態 or 重篤な疾患.
患者は重篤な状態で集中治療室に運ばれた。
The patient was taken to the ICU in critical condition.
この病気は放置すると重篤な合併症を引き起こす可能
If left untreated, this disease can cause serious complications.
Compound of 重 (heavy, serious) and 篤 (grave, serious). The kanji combination reinforces the meaning of extreme severity, typically in a medical context.