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 lethality (audio) \ noun
lethally \ ˈlē-​thə-​lē How to pronounce lethally (audio) \ 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

Sometimes the battle is over the risks of lethal injection. Richard Wolf, USA TODAY, "Conservative gains at Supreme Court leading to anger, frustration and 'peeks behind the curtain'," 9 June 2019 Spradley had been sentenced to death by lethal injection in 2008 by former Jefferson County Circuit Judge Gloria Bahakel in the murder of 58-year-old Center Point resident Marlene Jason. Howard Koplowitz | Hkoplowitz@al.com, al.com, "Ex-Alabama death row inmate Montez Spradley facing federal gun charge," 7 June 2019 When close friends are taken away—sometimes noisily resisting—for lethal injections, there is added turmoil. The Economist, "What it’s like to spend half a life in solitary confinement," 5 June 2019 Access to lethal means, such as a firearm or medication, is another consideration. Elizabeth Bernstein, WSJ, "Can Suicide Be Prevented?," 19 Jan. 2019 That’s why limiting access to lethal means is so powerful. German Lopez, Vox, "Guns killed more people than car crashes in 2017," 11 Dec. 2018 Get our daily newsletter In practical terms, measures that increase the distance between a suicidal thought and access to lethal means can make a big difference. The Economist, "Suicide is born of despair. Suicide prevention is far from hopeless," 14 June 2018 While this is not always easy, asking if the at-risk person has a plan and removing or disabling the lethal means can make a difference. Todd Ackerman, Houston Chronicle, "18 signs & symptoms of suicidal depression (Plus: How to help)," 8 June 2018 Firearms were involved in half of suicides — in part because a gun is a very lethal means. NBC News, "How can we help prevent suicides? Ask and listen, doctors say," 8 June 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

13 Jun 2019

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Time Traveler for lethal

The first known use of lethal was circa 1604

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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 lethality (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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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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behavior toward others

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