lethal

1 of 2

adjective

le·​thal ˈlē-thəl How to pronounce lethal (audio)
1
a
: of, relating to, or causing death
death by lethal injection
b
: capable of causing death
lethal chemicals
2
: gravely damaging or destructive : devastating
a lethal attack on his reputation
3
: very potent or effective
a lethal fastball
also : having a high alcohol content
a lethal rum punch
lethality noun
lethally adverb

lethal

2 of 2

noun

1
: an abnormality of genetic origin causing the death of the organism possessing it
2
Choose the Right Synonym for lethal

deadly, mortal, fatal, lethal mean causing or capable of causing death.

deadly applies to an established or very likely cause of death.

a deadly disease

mortal implies that death has occurred or is inevitable.

a mortal wound

fatal stresses the inevitability of what has in fact resulted in death or destruction.

fatal consequences

lethal applies to something that is bound to cause death or exists for the destruction of life.

lethal gas

Examples of lethal in a Sentence

Adjective a potentially lethal dose of a drug He was sentenced to death by lethal injection.
Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Adjective
If his confidence and rhythm have climbed to another level, Cincinnati's offense could look even more lethal. Cecil Merkerson Iii, MSNBC Newsweek, 29 Aug. 2025 The 2022 bare-knuckle holiday sensation Violent Night followed an embittered Santa, armed with lethal combat skills, who takes out a team of ruthless mercenaries to rescue a girl and her family. Justin Kroll, Deadline, 28 Aug. 2025
Noun
Almost 8 of 10 lethal overdose victims had no contact with the agency before their deaths, the report found. Washington Post, 4 Sep. 2020 In response to Russian operations and Chinese advances, the USAF is battling for air superiority in the Arctic with its most valuable—and lethal—assets in Alaska, including the F-22A Raptor and F-35A Joint Strike Fighter. Jeff Bolton, Popular Mechanics, 19 July 2020 See All Example Sentences for lethal

Word History

Etymology

Adjective and Noun

Latin letalis, lethalis, from letum death

First Known Use

Adjective

circa 1604, in the meaning defined at sense 1a

Noun

1917, in the meaning defined at sense 1

Time Traveler
The first known use of lethal was circa 1604

Browse Nearby Words

Cite this Entry

“Lethal.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/lethal. Accessed 5 Sep. 2025.

Kids Definition

lethal

1 of 2 adjective
le·​thal ˈlē-thəl How to pronounce lethal (audio)
: causing or capable of causing death
lethal chemicals
lethally adverb

lethal

2 of 2 noun

Medical Definition

lethal

1 of 2 adjective
le·​thal ˈlē-thəl How to pronounce lethal (audio)
: of, relating to, or causing death
a lethal injury
also : capable of causing death
lethal chemicals
a lethal dose
lethality noun
plural lethalities
lethally adverb

lethal

2 of 2 noun
1
: an abnormality of genetic origin causing the death of the organism possessing it usually before maturity
2

More from Merriam-Webster on lethal

Last Updated: - Updated example sentences
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