Referring to a crisis.
Extremely serious.
Being in or approaching a state of crisis in a disease.
Pertaining to a period of crisis in a person with a life-threatening medical condition. In critical or intensive care, doctors use technologically sophisticated equipment to treat and monitor the conditions of people who are recovering from surgery or who have experienced life-threatening problems such as heart attacks or severe injuries or burns.
The term “critically ill” is employed to indicate a state of severe illness or to describe a critical condition in which a patient may not experience recovery.