LETHAL Synonyms: 63 Similar and Opposite Words

Q: How does the adjective 'lethal' differ from other similar words?

Some common synonyms of lethal are deadly , fatal , and mortal . While all these words mean "causing or capable of causing death," lethal applies to something that is bound to cause death or exists for the destruction of life. // lethal gas

Q: When is 'deadly' a more appropriate choice than 'lethal'?

The words deadly and lethal can be used in similar contexts, but deadly applies to an established or very likely cause of death. // a deadly disease

Q: When could 'fatal' be used to replace 'lethal'?

Although the words fatal and lethal have much in common, fatal stresses the inevitability of what has in fact resulted in death or destruction. // fatal consequences

Q: When might 'mortal' be a better fit than 'lethal'?

While in some cases nearly identical to lethal , mortal implies that death has occurred or is inevitable. // a mortal wound

lethal

adjective

ˈlē-thəl

Definition of lethal

as in deadly

likely to cause or capable of causing death we were lucky that the snake's venom wasn't lethal, and our friend turned out to be all right

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How does the adjective lethal differ from other similar words?

Some common synonyms of lethal are deadly, fatal, and mortal. While all these words mean "causing or capable of causing death," lethal applies to something that is bound to cause death or exists for the destruction of life.

lethal gas

When is deadly a more appropriate choice than lethal?

The words deadly and lethal can be used in similar contexts, but deadly applies to an established or very likely cause of death.

a deadly disease

When could fatal be used to replace lethal?

Although the words fatal and lethal have much in common, fatal stresses the inevitability of what has in fact resulted in death or destruction.

fatal consequences

When might mortal be a better fit than lethal?

While in some cases nearly identical to lethal, mortal implies that death has occurred or is inevitable.

a mortal wound

Example Sentences

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.

Recent Examples of lethal Trump’s approval of Hasan’s execution last Friday came days after a botched lethal-injection execution in Tennessee. — Lorraine Ali, Los Angeles Times, 10 Oct. 2026 With its lethal heat and unforgiving terrain, the desert was dangerous enough without outsiders squaring off against Border Patrol. — Ryan Devereaux, ProPublica, 10 Oct. 2026 Last week, Tennessee death row inmate Christa Pike survived after prison officials injected her with two rounds of lethal drugs. — Lia Russell, Sacbee.com, 9 Oct. 2026 In February 2024, Idaho also failed to put a prisoner to death by lethal injection — the first unsuccessful execution attempt in the state’s history. — Idaho Statesman, 9 Oct. 2026 See All Example Sentences for lethal

Recent Examples of Synonyms for lethal

Adjective

Measles usually kills two or three people in every 1,000 cases, the WHO says, but the disease can be more deadly in poorer nations because of factors such as malnutrition.

— Arkansas Online, Arkansas Online, 18 Oct. 2026
The deadly fire erupted Saturday at Canadian Forces Base Wainwright, where fierce winds fueled flames that spread beyond the installation and into surrounding rural areas.

— Stephen Sorace, FOXNews.com, 18 Oct. 2026

Definition of deadly

Adjective

In 2006, a 45-year-old with a heart condition suffered a fatal heart attack while aboard the park's Goliath ride.

— DEMOCRAT-GAZETTE STAFF FROM WIRE REPORTS, Arkansas Online, 13 Oct. 2026
Mystery still surrounds the fatal shooting on the set of Alec Baldwin’s Western Rust, an incident that claimed the life of cinematographer Halyna Hutchins.

— Matthew Carey, Deadline, 12 Oct. 2026

Definition of fatal

Adjective

With the throne disengaged from governance, petitions and reports from officials piled up unread, crucial state posts went unfilled, and the imperial bureaucracy splintered amid poisonous factional infighting.

— Carl Minzner, Foreign Affairs, 5 Oct. 2026
With this potential even more poisonous investments in the bloated and indebted Paramount behemoth, there’s even more reason to reject it.

— Abigail Disney, New York Daily News, 28 Sep. 2026

Definition of poisonous

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let go

lethal

lethargic

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“Lethal.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/lethal. Accessed 19 Oct. 2026.

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Synonyms of lethal

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