deadly

adjective

dead·ly | \ ˈded-lē

deadlier; deadliest

Definition of deadly

(Entry 1 of 2)

1 : likely to cause or capable of producing death deadly poison

2a : 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

3a : 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

deadly

adverb

Definition of deadly (Entry 2 of 2)

1 archaic : in a manner to cause death : mortally

2 : suggesting death

3 : extremely deadly serious

Other Words from deadly Synonyms & Antonyms Choose the Right Synonym More Example Sentences Learn More about deadly

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Choose the Right Synonym for deadly

Adjective

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

Adjective

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.

Examples of deadly in a Sentence

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.

Recent Examples on the Web: Adjective

This was perhaps the deadliest, most intense form of ancient warfare. — William Gurstelle, Popular Mechanics, "How to Storm a Castle," 11 Apr. 2019 Although the voyages are deadlier, the number of migrants taking them is sharply down this year. — Frances D’emilio, BostonGlobe.com, "UN: June saw ‘exceptional’ rate of deaths in sea off Libya," 6 July 2018 That concept, which springs from Charles Darwin’s theory of evolution, is guiding new approaches to fighting this common and deadly disease. — James Degregori, STAT, "Using the principles of evolution to treat and prevent cancer," 27 June 2018 Many of these cleaners contain corrosive alkalis, which can have grave effects on your gastrointestinal track and respiratory system if inhaled and can be deadly if swallowed. — Lindsey Campbell, House Beautiful, "19 Dangerous Household Items You Should Quit Using Immediately," 15 Feb. 2019 But the system for apprehending and detaining children and families is in crisis — and the consequences have been deadly. — Dara Lind, Vox, "Trump administration to release hundreds of immigrant families from detention," 27 Dec. 2018 But for a teen in Malaysia, this common practice turned deadly. — Brittney Mcnamara, Teen Vogue, "A Teen Died After Reportedly Being Shocked by His Headphones," 10 Dec. 2018 The system, called the Maneuvering Characteristics Augmentation System, or MCAS, has been under scrutiny in another deadly 737 MAX crash last year. — Matina Stevis-gridneff, WSJ, "Ethiopian Airlines Boss Says Stall-Prevention System Likely Activated on Crashed 737 MAX," 25 Mar. 2019 Meanwhile, investigators have reported that the plane received a replacement angle-of-attack sensor (a system that measures whether the plane's nose is too high relative to the current of air) the day before the deadly crash. — Barbara S. Peterson, Popular Mechanics, "A Sensor Was Replaced One Day Before Lion Air Flight JH 610 Crashed," 8 Nov. 2018

Recent Examples on the Web: Adverb

Demonstrations on the Gaza-Israel border have picked up in the past two weeks, sometimes turning deadly as protesters have clashed with Israel’s security forces. — Dov Lieber, WSJ, "Six Palestinians Die in Clashes at Gaza-Israel Border," 28 Sep. 2018 Schlenk used his next two picks with that in mind: Maryland’s Kevin Huerter (deadly from the outside) and Villanova forward Omari Spellman, who plays a creative offensive game and can hit the three-pointer. — Bruce Jenkins, SFChronicle.com, "As the Warriors go their way, the big men multiply," 23 June 2018 OLYMPIA — Community advocates, law-enforcement groups and state lawmakers are vowing to quickly approve the compromise legislation that was thrown out by the courts earlier this year to change Washington’s police deadly-use-of-force law. — Joseph O’sullivan, The Seattle Times, "Community advocates, law enforcement groups call for Legislature to pass compromise bill on police deadly force," 3 Dec. 2018 The economic consequences of peace were deadly, and the astronomic reparations Berlin was forced to pay continued to sabotage its economic recovery. — Josef Joffe, WSJ, "Is Germany Slouching Toward Weimar Again?," 23 Sep. 2018 In Charlottesville, Virginia, marking one year since a white nationalist rally turned deadly. — Fox News, "Diamond & Silk sound off on Chicago violence," 12 Aug. 2018 The on-again, off-again summit meeting scheduling had all the earmarks of a television cliffhanger from a president who made a name for himself hosting a reality show on NBC for 14 years, only this time there were deadly serious consequences. — Peter Baker, New York Times, "Trump Announces Summit Meeting With Kim Jong-un Is Back on," 1 June 2018 The night turned deadly at about 11 p.m. when police were called to the 1600 block of Pentwood Road in Northeast Baltimore. — Lauren Lumpkin, baltimoresun.com, "2 killed, 2 injured in overnight shootings in Baltimore," 8 July 2018 In some cases, that abuse turns deadly: On average, between four and seven American children die each day because of abuse and neglect. — Gaby Del Valle, Teen Vogue, "How Child Abuse Affects the Brain," 22 June 2018

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.