noun
emaciation; severe weight loss
Medical term for pathological wasting or extreme thinness, often due to illness or malnutrition.
長期の闘病で、患者はるいそうが進んでいた。
Due to the long illness, the patient had become severely emaciated.
るいそうの原因を調べるために、精密検査を受けた。
I underwent a thorough examination to find the cause of the severe weight loss.