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

Synonyms & Similar Words

Relevance

Antonyms & Near Antonyms

Synonym Chooser

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 Deputies later fired a less-lethal beanbag round toward the Volkswagen before approaching it. — Daniel Hunt august 29, Sacbee.com, 29 Aug. 2026 Officials determined that two nurses had mixed the vaccine with a lethal dose of muscle relaxant. — Beth Mole, ArsTechnica, 28 Aug. 2026 Vatanka says that street protests alone won't be enough to bring change against a regime willing to use lethal force. — Greg Myre, NPR, 28 Aug. 2026 If executed, the agency said Humphreys will be the 55th inmate to be put to death by lethal injection in the state. — Caroline Silva, AJC.com, 27 Aug. 2026 See All Example Sentences for lethal

Recent Examples of Synonyms for lethal

Adjective

The death toll from a Russian strike on a warehouse west of Kyiv, the war's deadliest attack so far this year, rose to 38 with four people still missing, Ukrainian President Volodymyr Zelenskyy said on social media Sunday.

— ABC News, ABC News, 30 Aug. 2026
Ukraine launched deadly strikes in recent months on the facilities of Russia’s biggest online retailer, Wildberries, saying the company sells dual-use goods that have aided the Kremlin’s war effort.

— Samya Kullab, Los Angeles Times, 30 Aug. 2026

Definition of deadly

Adjective

An incident that for others might be fatal—a free fall from a high bridge—affects the coyote for only a brief moment.

— Zach Helfand, New Yorker, 31 Aug. 2026
There is a broad debate over the applicability of PNB to modern anti-trust cases, with many legal scholars finding the application of a random number, without any real analysis of the potential harm a merger might cause, to be a fatal flaw.

— Shubha Ghosh, Fortune, 31 Aug. 2026

Definition of fatal

Adjective

But the point was just that Nick’s character is emulating Sheridan’s poisonous corrupted values, and the internet is a vehicle for that relationship.

— Brian Davids, HollywoodReporter, 27 Aug. 2026
For this reason, these poisonous mushrooms are more commonly confused with other types of edible mushrooms like chicken of the woods and chanterelles (more on these in a minute).

— Katie Hill, Outdoor Life, 6 Aug. 2026

Definition of poisonous

Browse Nearby Words

let go

lethal

lethargic

See all Nearby Words

Cite this Entry

Style

“Lethal.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/lethal. Accessed 1 Sep. 2026.

Copy Citation

Synonyms of lethal

adjective

Synonym Chooser

Example Sentences

Browse Nearby Words

Cite this Entry

More from Merriam-Webster

Word of the Day

conscientious

Popular in Grammar & Usage

A Who’s Who Regarding ‘Who’s’ and ‘Whose’

Is it 'nerve-racking' or 'nerve-wracking'?

What's the difference between 'fascism' and 'socialism'?

Why does English have so many silent letters?

7 Pairs of Commonly Confused Words

Popular in Wordplay

Ye Olde Nincompoop: Old-Fashioned Words for 'Stupid'

14 Phobias You Probably Haven't Heard Of

Even More Words That Sound Like Insults But Aren't

Even More Bird Names that Sound Like Insults (and Sometimes Are)

12 Lovely and Unusual Words for the Natural World

Popular

A Who’s Who Regarding ‘Who’s’ and ‘Whose’

Ye Olde Nincompoop: Old-Fashioned Words for 'Stupid'

14 Phobias You Probably Haven't Heard Of

Games & Quizzes