To an extreme:
Being able or likely to do harm.
Used as an intensive:
Not safe; dangerous.
The definition of touch and go refers to an uncertain situation where an outcome is not clear and could change any minute.
Involving death or calling for the death penalty:
The definition of serious is showing deep thought, not joking, or a situation that requires careful thought.
Unsparing, harsh, or strict, as in treatment of others:
Causing grief, pain, or anguish:
Fraught with danger or harm:
Find another word for life-threatening. In this page you can discover 26 synonyms, antonyms, idiomatic expressions, and related words for life-threatening, like: deadly, dangerous, mortal, hazardous, unsafe, threatening, debilitating, fatal, touch-and-go, capital and serious.