deadly

adjective dead·ly \ ˈded-lē \

Definition of deadly

deadlier; deadliest

1 :likely to cause or capable of producing death

deadly poison

2 a :aiming to kill or destroy :implacable

a deadly enemy

b :highly effective

a deadly exposé

c :unerring

a deadly marksman

d :marked by determination or extreme seriousness

3 a :tending to deprive of force or vitality

a deadly habit

b :suggestive of death especially in dullness or lack of animation

deadly bores

a deadly conversation

4 :very great :extreme

—

deadliness

noun

See deadly defined for English-language learners

See deadly defined for kids

Examples of deadly in a Sentence

the world's most deadly snake
a more deadly form of the disease
They launched a deadly attack.
Officers are allowed to use deadly force if necessary.
She shoots with deadly accuracy.
a basketball player with deadly aim
A deadly silence followed his question.
The two gang leaders are deadly enemies.
He spoke with deadly seriousness.

Recent Examples of deadly from the Web

TONTO NATIONAL FOREST, Ariz. (AP) — Adults, teens and children as young as 2 were enjoying a summer afternoon by cooling off in an Arizona creek when the gentle waters turned deadly.

— anita snow, The Seattle Times, "Flash flood kills 5 children, 4 adults at Arizona swim hole," 17 July 2017
This year, there will be an estimated 87,000 new cases of melanoma, the deadliest form of skin cancer.

— kathy r. byrnes, Cincinnati.com, "Sun, cancer and vitamin D: Top 5 myths and facts," 16 July 2017
The noxious gases that flame retardants emit during fires can be deadly in their own right.

— anne kniggendorf, kansascity, "Today’s homes burn faster than ones in the past, and your furniture may be to blame," 14 July 2017
Some of this speculation can be deadly serious (imagine America’s electricity grid being knocked out—

— The Economist, "The joy of hypotheticals," 13 July 2017
The citation with his medal describes the soldier’s actions during a 2007 ambush of his unit in the deadly Korengal Valley.

— jeanette steele, sandiegouniontribune.com, "Afghanistan Medal of Honor soldier gives his award to former brigade," 7 July 2017
This year, however, the shadow seemed deeper, darker, and somehow more poisonous, like a deadly cloud of gas over an uncertain battlefield.

— charles p. pierce, Esquire, "The Great American Shadow," 5 July 2017
Dallas Cowboys linebacker Damien Wilson was arrested on two counts of aggravated assault with a deadly weapon after he was accused of backing his truck into a woman and threatening a man with a rifle during a dispute with some tailgaters.

— New York Times, "Lionel Messi and Barcelona Agree on Extension," 5 July 2017
Dallas Cowboys linebacker Damien Wilson has been charged with two counts of aggravated assault with a deadly weapon, Frisco police said Wednesday.

— drew davison, star-telegram.com, "Cowboys LB Damien Wilson arrested in Frisco on aggravated assault charges," 5 July 2017

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

First Known Use of deadly

before 12th century

deadly Synonyms

Synonyms

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

Antonyms

healthful, healthy, nonfatal, nonlethal, wholesome

Near Antonyms

beneficial, restorative, salubrious, salutary; alleviative, corrective, curative, remedial, tonic; advantageous, beneficial, useful; nonpoisonous, nontoxic, safe

Synonym Discussion of deadly

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

deadly

adverb

Definition of deadly

1 archaic :in a manner to cause death :mortally

2 :suggesting death

3 :extremely

deadly serious

See deadly defined for English-language learners

Examples of deadly in a Sentence

I'm deadly serious about making an offer on the house.

Recent Examples of deadly from the Web

The coming storm, he had been warned, could turn deadly.

— wesley lowery and avi selk, chicagotribune.com, "'He laid down his life': Houston police officer among Harvey's victims," 29 Aug. 2017
The coming storm, he had been warned, could turn deadly.

— wesley lowery, Washington Post, "Harvey’s death toll rises amid stories of harrowing attempts to escape rising waters," 29 Aug. 2017
And then there was the city’s deepening conflict with the radical group MOVE, which turned deadly in 1978 when Officer James Ramp was fatally shot during one standoff, and one unarmed member of the group was beaten by cops.

— david gambacorta, Philly.com, "Was Frank Rizzo racist, or a product of his time?," 22 Aug. 2017
Demonstrations by white supremacist groups in Charlottesville on Aug. 12 turned deadly after a neo-Nazi plowed a car into a crowd, killing one counterprotester and injuring at least 19 other people.

— the washington post, AL.com, "University of Texas removes 4 Confederate statues," 21 Aug. 2017
A statue of Lee was at the heart of a violent protest in Charlottesville, Virginia, that turned deadly a week ago.

— jonathan drew, The Seattle Times, "Duke University removes statue of Confederate general," 19 Aug. 2017
Another statue of Lee, the top Confederate general during the Civil War, was the focus of the violent protest in Charlottesville, Virginia, that turned deadly a week ago.

— Bloomberg.com, "Duke University Removes Damaged Robert E. Lee Statue," 19 Aug. 2017
The rally turned deadly, however, when an Ohio man allegedly rammed a gray Dodge Challenger into a crowd of counter-protesters, killing one woman and injuring at least 19 others.

— javonte anderson, Post-Tribune, "In wake of Charlottesville tragedy, Indiana lawmakers hope for new effort to pass hate crime bill," 16 Aug. 2017
Beyond being deadly, such fires are also very costly.

— joshua emerson smith, sandiegouniontribune.com, "Are wildfires worsening due to development, climate change and controversial forest management?," 7 July 2017

First Known Use of deadly

before 12th century

deadly Synonyms

Synonyms

achingly, almighty, archly, awful, awfully, badly, beastly, blisteringly, bone, colossally, corking, cracking, damn, damned, dang, very, desperately, eminently, enormously, especially, ever, exceedingly (also exceeding), extra, extremely, fabulously, fantastically, far, fiercely, filthy, frightfully, full, greatly, heavily, highly, hugely, immensely, incredibly, intensely, jolly, majorly, mightily, mighty, monstrous [chiefly dialect], mortally, most, much, particularly, passing, rattling, real, really, right, roaring, roaringly, seriously, severely, so, sore, sorely, spanking, specially, stinking, such, super, supremely, surpassingly, terribly, that, thumping, too, unco, uncommonly, vastly, vitally, way, whacking, wicked, wildly

Antonyms

little, negligibly, nominally, slightly, somewhat

Near Antonyms

meagerly, scantily; barely, hardly, just, marginally, minimally, scarcely

DEADLY Defined for English Language Learners

deadly

adjective

Definition of deadly for English Language Learners

: causing or able to cause death
: extremely accurate and effective
: extreme or complete

deadly

adverb

Definition of deadly for English Language Learners

: extremely or completely

DEADLY Defined for Kids

deadly

adjective dead·ly \ ˈded-lē \

Definition of deadly for Students

deadlier; deadliest

1 :causing or capable of causing death

deadly poisons

2 :meaning or hoping to kill or destroy

deadly enemies

3 :very accurate

He shot the arrow with deadly aim.

4 :¹extreme 1

Synonym Discussion of deadly

deadly, mortal, and fatal mean causing or capable of causing death. deadly is used of something that is certain or very likely to cause death.

- The mushroom contains a deadly poison.

mortal is used of something that already has caused death or is about to cause death.

- He received a mortal wound in battle.

fatal is used when death is certain to follow.

- The wounds proved to be fatal.

deadly

adverb

Definition of deadly for Students

1 :in a way suggestive of death

Her face was deadly pale.

2 :to an extreme degree

deadly dull

Medical Dictionary

deadly

adjective dead·ly \ ˈded-lē \

medical Definition of deadly

deadlier; deadliest

:likely to cause or capable of causing death

a deadly disease

a deadly poison

a deadly instrument

—

deadliness

play \-nəs\ noun

Law Dictionary

deadly

adjective dead·ly

legal Definition of deadly

deadlier; deadliest

:likely to cause or capable of causing death; also :dangerous 2

Note: Deadly and dangerous are sometimes used interchangeably, especially in connection with weapons or instruments.

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See words that rhyme with deadly Thesaurus: All synonyms and antonyms for deadly Spanish Central: Translation of deadly Nglish: Translation of deadly for Spanish speakers Britannica English: Translation of deadly for Arabic speakers

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deadly

Definition of deadly

deadliness

From the M-W Editors

Examples of deadly in a Sentence

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First Known Use of deadly

deadly Synonyms

Synonyms

Antonyms

Related Words

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Synonym Discussion of deadly

deadly

Definition of deadly

Examples of deadly in a Sentence

Recent Examples of deadly from the Web

First Known Use of deadly

deadly Synonyms

Synonyms

Antonyms

Related Words

Near Antonyms

DEADLY Defined for English Language Learners

deadly

Definition of deadly for English Language Learners

deadly

Definition of deadly for English Language Learners

DEADLY Defined for Kids

deadly

Definition of deadly for Students

Synonym Discussion of deadly

deadly

Definition of deadly for Students

Medical Dictionary

deadly

medical Definition of deadly

deadliness

Law Dictionary

deadly

legal Definition of deadly

Learn More about deadly

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