ˈlife-ˌthreatening adjective
a life-threatening situation, illness, or injury could cause a person to die ⇒ fatal

[TahlilGaran] Dictionary of Contemporary English ▲

serious very bad – used about problems, accidents, illnesses, or crimes:
Violent crime is a serious problem in and around the capital.
The boy was taken to hospital with serious head injuries.
Fortunately, the damage to the car was not serious.
severe very serious – used about problems, injuries, and illnesses:
He suffered severe injuries in a car crash.
The problem became so severe that they had to bring water in from other countries.
severe epilepsy
grave used about a situation that is very serious and worrying, especially because it is dangerous or seems likely to get worse:
A thick fog descended and I knew that we were in grave danger.
The situation is grave – war now seems inevitable.
acute used about an illness, problem, or situation that has become very serious or dangerous, and needs to be dealt with quickly:
She was taken to the hospital suffering from acute appendicitis.
In San Diego, the shortage of skilled workers is acute.
desperate used about a situation or problem that is very serious or dangerous, especially because a lot of people need urgent help:
The situation is desperate – people here need aid before the harsh winter sets in.
The hospital is full of people in desperate need of medical attention.
critical used about a situation that is very serious and dangerous and might get worse suddenly:
In 1991, the food supply situation became critical.
Eight people were killed and four are still in a critical condition.
life-threatening used about a situation, illness, or condition in which someone could die:
Her child had a potentially life-threatening illness.
The situation was not life-threatening, but it was very worrying.
be a matter of life and death spoken to be extremely serious – used when a situation is very urgent or important:
For people living with HIV, getting the right treatment is literally a matter of life and death.
solemn very serious because of an important or sad occasion or ceremony:
My father looked solemn, the way grown-ups look at funerals.
The judge read the verdict in a solemn voice.
sombre British English (also somber American English) /ˈsɒmbə $ ˈsɑːmbər/ written sad, quiet, or serious because something unpleasant or worrying has happened or is going to happen:
They sat in sombre silence.
The meeting began in a sombre mood.
earnest very serious and sincere – often used about someone who is young and not very experienced:
He was a rather earnest-looking young man.
‘That’s wrong,’ she said, her voice sounding very earnest.

[TahlilGaran] English Thesaurus ▲