serious illness; critical illness
A formal or literary term for a severe, life-threatening disease. Not used in casual conversation; more common in medical or legal contexts.
He was hospitalized due to a serious illness.
severely disabled person (ritsuryō system)
Archaic legal term from the ritsuryō codes, referring to a person with a heavy disability. Not used in modern Japanese outside historical contexts.
Under the ritsuryō system, severely disabled persons were exempted from taxes and labor.