deadly
1 of 2adjective
dead·ly ˈded-lē 
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
deadly
2 of 2adverb
1
archaic : in a manner to cause death : mortally
2
: suggesting death
3
: extremely
deadly serious
Synonyms
Adjective
- baleful
- deathly
- fatal
- fell
- killer
- lethal
- mortal
- murderous
- pestilent
- terminal
- vital
Adverb
- achingly
- almighty
- archly
- awful
- awfully
- badly
- beastly
- blisteringly
- bone
- colossally
- corking
- cracking
- damn
- damned
- dang
- desperately
- eminently
- enormously
- especially
- ever
- exceedingly
- 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
- very
- vitally
- way
- whacking
- wicked
- wildly
See all Synonyms & Antonyms 
Example Sentences
Adjective 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. Adverb I'm deadly serious about making an offer on the house. See More
Recent Examples on the Web
Richard Tribou, Orlando Sentinel, 18 Sep. 2022 Most residents are more concerned about deadly street crime than air pollution. John Lippert, Chicago Tribune, 18 Sep. 2022 The deadly impact of illicit pills can be profound, with fentanyl being 100 times stronger than morphine and 50 times stronger than heroin, according to the federal Centers for Disease Control and Prevention. Los Angeles Times, 17 Sep. 2022 Medusa, for example, is a snake-haired demon who tricks men with her lethal gaze — a deadly symbol of female cunning, during a time when such stories were considered to be a quasi-historical reality. Rachel Ashcroft, Longreads, 17 Sep. 2022 In 2019, Typhoon Hagibis produced a record deluge that caused deadly flooding and landslides in highly populated areas of northern Japan, killing more than 80 people. Rachel Pannett, Washington Post, 17 Sep. 2022 The deadly accident was the second to occur this month. Louis Casiano, Fox News, 17 Sep. 2022 Elsewhere in Ukraine, Russian forces kept pounding cities and villages with deadly missile strikes and shelling. Jon Gambrell, BostonGlobe.com, 17 Sep. 2022 Spanning over 120 years of literature, these dystopian novels feature totalitarian governments, menacing villains, and the causes of our downfall from deadly diseases to climate change to each other. Robert English, EW.com, 17 Sep. 2022 Aaron Boxerman, WSJ, 31 Aug. 2022 Some encampment fires have turned deadly, like a February inferno at an encampment under a San Francisco I-280 on-ramp. Lauren Hepler, San Francisco Chronicle, 30 Aug. 2022 My colleague Jack Dolan wrote a gripping story about a recent attempt to summit that turned deadly — and the controversial climbing practice that critics say gives a false sense of security to amateur climbers. Sammy Rothstaff Writer, Los Angeles Times, 26 Aug. 2022 The dispute then turned deadly when Mr. Guzman choked Ms. Grayson to death. Caroline Silva, ajc, 8 Aug. 2022 Much of the Northwest remains under heat alerts today following a week of extreme temperatures that turned deadly. Alexandra Meeks, CNN, 1 Aug. 2022 Notorious cartel leader Rafael Caro Quintero, who is portrayed in the Netflix series Narcos: Mexico, has been captured after a lengthy manhunt that turned deadly. Justine Browning, EW.com, 16 July 2022 Some incidents turned deadly, including a college football game in Durham, North Carolina, on Sept. 18, where police said two people were fatally shot. Bill Hutchinson, ABC News, 1 May 2022 One man is dead, and another is behind bars after a dispute during a card game turned deadly in Shelby County. Carol Robinson | Crobinson@al.com, al, 23 Aug. 2022 See More
Adjective
With Fiona due just two days before the anniversary of Hurricane Maria, a deadly Category 4 storm that hit on Sept. 20, 2017, anxiety levels ran high across the island. Richard Tribou, Orlando Sentinel, 18 Sep. 2022 Most residents are more concerned about deadly street crime than air pollution. John Lippert, Chicago Tribune, 18 Sep. 2022 The deadly impact of illicit pills can be profound, with fentanyl being 100 times stronger than morphine and 50 times stronger than heroin, according to the federal Centers for Disease Control and Prevention. Los Angeles Times, 17 Sep. 2022 Medusa, for example, is a snake-haired demon who tricks men with her lethal gaze — a deadly symbol of female cunning, during a time when such stories were considered to be a quasi-historical reality. Rachel Ashcroft, Longreads, 17 Sep. 2022 In 2019, Typhoon Hagibis produced a record deluge that caused deadly flooding and landslides in highly populated areas of northern Japan, killing more than 80 people. Rachel Pannett, Washington Post, 17 Sep. 2022 The deadly accident was the second to occur this month. Louis Casiano, Fox News, 17 Sep. 2022 Elsewhere in Ukraine, Russian forces kept pounding cities and villages with deadly missile strikes and shelling. Jon Gambrell, BostonGlobe.com, 17 Sep. 2022 Spanning over 120 years of literature, these dystopian novels feature totalitarian governments, menacing villains, and the causes of our downfall from deadly diseases to climate change to each other. Robert English, EW.com, 17 Sep. 2022 Adverb
The games turned deadly after members of the Black September terrorist group entered the Olympic Village, killing two Israeli athletes and taking nine others hostage. Aaron Boxerman, WSJ, 31 Aug. 2022 Some encampment fires have turned deadly, like a February inferno at an encampment under a San Francisco I-280 on-ramp. Lauren Hepler, San Francisco Chronicle, 30 Aug. 2022 My colleague Jack Dolan wrote a gripping story about a recent attempt to summit that turned deadly — and the controversial climbing practice that critics say gives a false sense of security to amateur climbers. Sammy Rothstaff Writer, Los Angeles Times, 26 Aug. 2022 The dispute then turned deadly when Mr. Guzman choked Ms. Grayson to death. Caroline Silva, ajc, 8 Aug. 2022 Much of the Northwest remains under heat alerts today following a week of extreme temperatures that turned deadly. Alexandra Meeks, CNN, 1 Aug. 2022 Notorious cartel leader Rafael Caro Quintero, who is portrayed in the Netflix series Narcos: Mexico, has been captured after a lengthy manhunt that turned deadly. Justine Browning, EW.com, 16 July 2022 Some incidents turned deadly, including a college football game in Durham, North Carolina, on Sept. 18, where police said two people were fatally shot. Bill Hutchinson, ABC News, 1 May 2022 One man is dead, and another is behind bars after a dispute during a card game turned deadly in Shelby County. Carol Robinson | Crobinson@al.com, al, 23 Aug. 2022 See More Word History
First Known Use
Adjective
before the 12th century, in the meaning defined at sense 1
Adverb
before the 12th century, in the meaning defined at sense 1
Phrases Containing deadly
Kids Definition
deadly 1 of 2
adjective
dead·ly ˈded-lē
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
: extreme entry 1 sense 1
deadly
2 of 2adverb
1
: in a way suggestive of death
Her face was deadly pale.
2
: to an extreme degree
deadly dull
Medical Definition
deadly
adjective
dead·ly ˈded-lē
deadlier; deadliest
: likely to cause or capable of causing death
a deadly disease
a deadly poison
a deadly instrument
Legal Definition
deadly
adjective
dead·ly
deadlier; deadliest
: likely to cause or capable of causing death
also : dangerous sense 2
Note: Deadly and dangerous are sometimes used interchangeably, especially in connection with weapons or instruments.
deadly 1 of 2
adjective
1
as in lethal
likely to cause or capable of causing death the doctors were alarmed about the outbreak of the deadly new virus Synonyms & Similar Words
Relevance
- lethal
- fatal
- poisonous
- infectious
- dangerous
- harmful
- killer
- toxic
- infective
- murderous
- terminal
- destructive
- deathly
- hazardous
- fell
- mortal
- injurious
- pernicious
- virulent
- vital
- deleterious
- baleful
- pestilent
- perilous
- risky
- serious
- noxious
- threatening
- baneful
- menacing
- ugly
- bloody
- pestilential
- sublethal
- unhealthy
- jeopardizing
- grievous
- grave
- truculent
- sanguinary
- parlous
- unsound
- internecine
- sanguine
Antonyms & Near Antonyms
- nonfatal
- nonlethal
- beneficial
- healthful
- healthy
- wholesome
- salubrious
- beneficial
- salutary
- restorative
- curative
- corrective
- useful
- remedial
- advantageous
- safe
- tonic
- nontoxic
- nonpoisonous
- alleviative
2
as in sheer
having no exceptions or restrictions the deadly tedium of waiting for the fog to lift Synonyms & Similar Words
- sheer
- simple
- unconditional
- pure
- utter
- complete
- absolute
- total
- outright
- very
- damned
- damn
- dreadful
- perfect
- definite
- profound
- real
- downright
- huge
- unmitigated
- endless
- crashing
- stone
- regular
- horrible
- thorough
- thoroughgoing
- unadulterated
- stark
- terrible
- blooming
- categorical
- clean
- dead
- bodacious
- unqualified
- out-and-out
- constant
- all-out
- consummate
- blank
- plumb
- straight-out
- unalloyed
- fair
- flat-out
- arrant
- extreme
- genuine
- eternal
- rank
- flat
- classic
- veritable
- perpetual
- categoric
- authentic
- extraordinary
- hopeless
- unremitting
- frightful
- undying
- unrestricted
- terrific
- main
- habitual
- supreme
- superlative
- inveterate
- surpassing
- confirmed
Antonyms & Near Antonyms
- uncertain
- questionable
- doubtful
- dubious
- restricted
- qualified
- equivocal
3
as in mortal
of, relating to, or suggestive of death a deadly pallor spread across her face as the tragic news gradually sank in Synonyms & Similar Words
- lethal
- mortal
- dead
- spectral
- murderous
- deathly
- fatal
- mortuary
- fell
- phantom
- killer
- ghostly
- still
- inert
- lifeless
- macabre
- inactive
- fateful
- quiescent
- inoperative
- ghostlike
- cadaverous
- baleful
- pestilent
Antonyms & Near Antonyms
- active
- breathing
- live
- alive
- vigorous
- living
- vital
- energetic
- spirited
- frisky
- animate
- vivacious
- brisk
- jazzy
- lively
- animated
- perky
- well
- racy
- peppy
- zippy
- healthy
- sprightly
- springy
- robust
- gay
- whole
- bouncing
- snappy
- wholesome
- sound
- jaunty
- pert
- spanking
- sparky
- sprightful
- hale
- hearty
- fit
- chipper
- able-bodied
deadly
2 of 2adverb
as in extremely
to a great degree I'm deadly serious about making an offer on the house Synonyms & Similar Words
- extremely
- incredibly
- terribly
- very
- damned
- damn
- highly
- too
- badly
- that
- super
- so
- severely
- jolly
- real
- awful
- seriously
- intensely
- full
- wicked
- really
- mighty
- desperately
- most
- far
- wildly
- filthy
- such
- exceptionally
- monstrous
- especially
- good and
- heavily
- fiercely
- greatly
- awfully
- frightfully
- fantastically
- much
- particularly
- uncommonly
- stinking
- beastly
- exceedingly
- fabulously
- passing
- roaring
- way
- immensely
- dang
- mortally
- exceeding
- supremely
- specially
- surpassingly
- hugely
- absolutely
- vitally
- almighty
- extra
- sore
- eminently
- utterly
- remarkably
- cracking
- rattling
- bone
- unco
- achingly
- whacking
- vastly
- enormously
- thumping
- totally
- thoroughly
- blisteringly
- deeply
- sorely
- positively
- a lot
- corking
- colossally
- completely
- spanking
- archly
- roaringly
- downright
- majorly
- ever
- entirely
- profoundly
- wholly
- significantly
- as all get-out
- right
- mightily
- radically
- fully
- considerably
- noticeably
- purely
- notably
- visibly
- substantially
- obviously
- extensively
- obscenely
- monstrously
- monumentally
- markedly
- flat-out
- excessively
- amazingly
- astonishingly
- palpably
- staggeringly
- astronomically
- altogether
- discernibly
- appreciably
- abundantly
- plentifully
- plainly
- grandly
- overmuch
Antonyms & Near Antonyms
- little
- somewhat
- slightly
- negligibly
- nominally
- hardly
- just
- scarcely
- minimally
- barely
- marginally
- meagerly
- scantily
Synonym Chooser
Some common synonyms of deadly are fatal, lethal, and mortal. While all these words mean "causing or capable of causing death," deadly applies to an established or very likely cause of death.
a deadly disease
In some situations, the words fatal and deadly are roughly equivalent. However, fatal stresses the inevitability of what has in fact resulted in death or destruction.
fatal consequences
While in some cases nearly identical to deadly, lethal applies to something that is bound to cause death or exists for the destruction of life.
lethal gas
The synonyms mortal and deadly are sometimes interchangeable, but mortal implies that death has occurred or is inevitable.
a mortal wound