le·​thal | \ ˈlē-thəl \

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 \ noun
lethally \ ˈlē-​thə-​lē \ adverb

Synonyms & Antonyms for lethal

Synonyms: Adjective

baleful, deadly, deathly, fatal, fell, killer, mortal, murderous, pestilent, terminal, vital

Antonyms: Adjective

healthful, healthy, nonfatal, nonlethal, wholesome

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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


a potentially lethal dose of a drug He was sentenced to death by lethal injection.

Recent Examples on the Web: Adjective

The paper also said North Korea is capable of cultivating lethal biological agents such as anthrax and smallpox that could be turned into weapons. Jonathan Cheng, WSJ, "Step One in Disarming North Korea: Knowing What’s in Kim’s Arsenal," 8 June 2018 In a history of the American gas chamber, Scott Christianson states that the fumigating agent Zyklon-B, which was licensed to American Cyanamid by the German company I. G. Farben, was considered as a lethal agent but found to be impractical. Naomi Fry, The New Yorker, "How American Racism Influenced Hitler," 23 Apr. 2018 Russia has disputed claims by the U.S. and its allies that Assad's forces used lethal chemical agents against civilians in Douma. David S. Cloud, latimes.com, "U.S. and allies fire missiles at Syria in retaliation for suspected poison gas attack," 14 Apr. 2018 The lethal nerve agent identified in the attack, Novichok is believed to be a military-grade chemical developed by Russia. Laignee Barron, Time, "Sergei Skripal's Daughter is Conscious and Rapidly Recovering From Nerve Agent Attack," 31 Mar. 2018 According to UK Prime Minister Theresa May, they were poisoned with a chemical weapon known as Novichok — one of the world’s most lethal nerve agents — in Salisbury, England, where Skripal lived. Alex Ward, Vox, "Putin just kicked out 150 Western diplomats. What comes next could be much worse.," 29 Mar. 2018 Six months later, Russia has been accused of secretly producing a strain of lethal nerve agents for years, in what would be a grave violation of its international commitments. Ellen Barry, BostonGlobe.com, "Russia, praised for scrapping chemical weapons, now under watchdog’s gaze," 21 Mar. 2018 His death — which is currently being reviewed by the Sacramento County District Attorney’s Office and has yet to result in any indictments — gained national attention as another instance of lethal police force enacted upon an unarmed black body. Lincoln Anthony Blades, Teen Vogue, "Stevante Clark is Running for Mayor of Sacramento," 3 Jan. 2019 This includes not selling facial recognition software to identify targets where lethal force may be used. Dina Bass, The Seattle Times, "Privacy groups urge tech firms to sign Safe Face Pledge to restrict use of facial recognition," 12 Dec. 2018

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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Statistics for lethal

Last Updated

7 Feb 2019

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Time Traveler for lethal

The first known use of lethal was circa 1604

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More Definitions for lethal



English Language Learners Definition of lethal

: causing or able to cause death


le·​thal | \ ˈlē-thəl \

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 \ 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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More from Merriam-Webster on lethal

Thesaurus: All synonyms and antonyms for lethal

Spanish Central: Translation of lethal

Nglish: Translation of lethal for Spanish Speakers

Britannica English: Translation of lethal for Arabic Speakers

Comments on lethal

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to express emotion in a dramatic way

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