Definitions

life-threatening

[lahyf-thret-ning, -thret-n-ing] / ˈlaɪfˌθrɛt nɪŋ, -ˌθrɛt n ɪŋ /

ADJECTIVE

very dangerous

Synonyms

STRONGEST

deadly lethal mortal serious severe

WEAK

capital critical hazardous threatening touch and go unsafe

Antonyms

STRONGEST

harmless invigorating

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

Please continue to call 999 in a life-threatening emergency.

From BBC • Jun. 4, 2026

"If these findings are confirmed in Phase III trials, we may finally be able to offer patients a targeted therapy that halts and potentially reverses liver damage before it progresses to life-threatening stages."

From Science Daily • May 27, 2026

“If I don’t do what’s medically indicated in a potentially life-threatening situation, then I am liable for neglect. Why isn’t this the same thing?”

From Salon • May 27, 2026

Amgen has said avacopan is an important and effective medicine that treats a rare and life-threatening disease, for which patients have few other options.

From The Wall Street Journal • May 21, 2026

The eight-man expedition was pinned down in a ferocious blizzard high on K2, waiting to make an assault on the summit, when a team member named Art Gilkey developed thrombophlebitis, a life-threatening altitude-induced blood clot.

From "Into Thin Air" by Jon Krakauer