le·​thal | \ ˈlē-thəl How to pronounce lethal (audio) \

Definition of lethal

 (Entry 1 of 2)

1a : 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



Definition of lethal (Entry 2 of 2)

1 : an abnormality of genetic origin causing the death of the organism possessing it

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Other Words from lethal


lethality \ lē-​ˈtha-​lə-​tē How to pronounce lethal (audio) \ noun
lethally \ ˈlē-​thə-​lē How to pronounce lethal (audio) \ adverb

Synonyms & Antonyms for lethal

Synonyms: Adjective

Antonyms: Adjective

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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: Adjective Ledell Lee was executed for murder in a flurry of lethal injections that divided the Supreme Court and proceeded despite lawyers’ calls for DNA testing. Washington Post, "Four years after a man’s execution, lawyers say DNA from the murder weapon points to someone else," 5 May 2021 In March, as a lethal second wave of the virus brought daily death tolls to unprecedented highs, Bolsonaro also reshuffled his wider cabinet, replacing six ministers in an apparent bid to secure greater loyalty. Rodrigo Pedroso And Caitlin Hu, CNN, "Bolsonaro was 'warned' about the consequences of ignoring science, inquiry hears," 5 May 2021 Sometimes the sharks do act curious about us newcomers, and given their potential for a probing lethal bite, those moments can be harrowing. Los Angeles Times, "Drones show California’s great white sharks are closer — and more common — than you think," 4 May 2021 Whitman was murdered by Cayuse Indians in 1847, near present-day Walla Walla, in the midst of a lethal measles outbreak. Arkansas Online, "Honoring a symbol of truth," 2 May 2021 The lethal removal of bison from the Grand Canyon has been a years-long point of contention between the park and Arizona wildlife officials. Shanti Lerner, USA TODAY, "Grand Canyon NP seeks 'skilled' hunters to reduce bison population inside the park," 30 Apr. 2021 Others are circumspect, our social skills atrophied and our inhibitions increased in response to a lethal disease. New York Times, "‘Romeo and Juliet’ Meets the Hot Vax Summer," 30 Apr. 2021 The Pride bring a similarly lethal attack to face the Courage, led by the front-line trio of Alex Morgan, Sydney Leroux and Marta. Julia Poe, orlandosentinel.com, "Orlando Pride face final Challenge Cup opponent in North Carolina," 30 Apr. 2021 Allen and Garland keep building chemistry and are showing flashes of a lethal two-man game. Chris Fedor, cleveland, "Cleveland Cavaliers’ late-season losses pushing them closer to what they need most," 29 Apr. 2021 Recent Examples on the Web: Noun Almost 8 of 10 lethal overdose victims had no contact with the agency before their deaths, the report found. Washington Post, "How a D.C. sex worker became the face of a city report on drug treatment failures," 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, "'That Others May Live': The Pararescue Units Preparing for War on Top of the World," 19 July 2020

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'lethal.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of lethal


circa 1604, in the meaning defined at sense 1a


1917, in the meaning defined at sense 1

History and Etymology for lethal

Adjective and Noun

Latin letalis, lethalis, from letum death

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Time Traveler for lethal

Time Traveler

The first known use of lethal was circa 1604

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Statistics for lethal

Last Updated

8 May 2021

Cite this Entry

“Lethal.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/lethal. Accessed 9 May. 2021.

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More Definitions for lethal



English Language Learners Definition of lethal

: causing or able to cause death


le·​thal | \ ˈlē-thəl How to pronounce lethal (audio) \

Medical Definition of lethal

 (Entry 1 of 2)

: of, relating to, or causing death a lethal injury also : capable of causing death lethal chemicals a lethal dose

Other Words from lethal

lethality \ lē-​ˈthal-​ət-​ē How to pronounce lethal (audio) \ noun, plural lethalities
lethally adverb



Medical Definition of lethal (Entry 2 of 2)

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

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