Mortal Danger is a term used to describe a situation that could lead to death or serious injury. It is often used to refer to situations that are particularly dangerous, such as extreme weather conditions or hazardous environments. The term can also be used to describe a person's vulnerability to harm, such as in the case of a medical condition or a dangerous lifestyle. The crossword solution for this term is 'PERIL', which is defined as a state of danger or great risk.