kill·​er | \ ˈki-lər How to pronounce killer (audio) \

Definition of killer

 (Entry 1 of 2)

1 : one that kills
3a : one that has a forceful, violent, or striking impact
b : one that is extremely difficult to deal with



Definition of killer (Entry 2 of 2)

1 : strikingly impressive or effective a killer smile a killer résumé
2 : extremely difficult to deal with a killer fastball also : causing death or devastation a killer tornado

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Synonyms & Antonyms for killer

Synonyms: Noun

bear, beast, chore, headache, job, labor

Synonyms: Adjective

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

Antonyms: Adjective

healthful, healthy, nonfatal, nonlethal, wholesome

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Examples of killer in a Sentence


Heart disease is the leading killer of both men and women. The chemical is used as a weed killer.


killer viruses that claimed millions of lives a killer exercise program guaranteed to whip you into shape
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Recent Examples on the Web: Noun

Harold Shipman was one of the most prolific serial killers in history. Hannah Fry, The New Yorker, "What Statistics Can and Can’t Tell Us About Ourselves," 2 Sep. 2019 Heart disease is far and away the number one killer in this country (some 1 in 4 deaths are associated with it). Sy Mukherjee, Fortune, "The Diseases That Are Increasingly Killing Americans: Brainstorm Health," 27 Aug. 2019 And in Mindhunter season 2, actor Oliver Cooper (of Project X and Californication fame) made for a seriously convincing fictional version of the killer. Heather Finn, Good Housekeeping, "What the Real 'Mindhunter' Season 2 Serial Killers Look Like Compared to the Actors," 24 Aug. 2019 Tuberculosis is the single leading infectious killer in the world, infecting an estimated 10 million people in 2017 and killing 1.6 million of them. Beth Mole, Ars Technica, "How a new antibiotic destroys extremely drug-resistant tuberculosis," 16 Aug. 2019 Viewers were obsessed with the hunky profiler who wasn't afraid to chase down the most dangerous serial killers in the country. Megan Stein, Country Living, "Here's the Real Reason Shemar Moore Left 'Criminal Minds'," 10 Aug. 2019 The men’s final featured Dora against Australia’s Liam O’Brien, who became a giant killer in the event. Joe Haakenson, Daily Pilot, "Sage Erickson wins U.S. Open of Surfing women’s title, denying rival Courtney Conlogue repeat," 4 Aug. 2019 For example, Stoneman Douglas reported no trespassing in 2017-18, even though the brother of the killer was arrested for trespassing a few weeks after the shooting. Scott Travis,, "South Florida school districts ‘most problematic’ in complying with safety laws," 25 July 2019 Chris Estrada, a friend of the killer, was sentenced to 42 months after his conviction for tampering with physical evidence. Dallas News, "Friend of man who killed Zuzu Verk in West Texas gets 3 1/2 years for evidence tampering," 12 July 2019

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

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First Known Use of killer


15th century, in the meaning defined at sense 1


1951, in the meaning defined at sense 1

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Dictionary Entries near killer





killer app

killer bar

killer bee

Statistics for killer

Last Updated

8 Sep 2019

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Time Traveler for killer

The first known use of killer was in the 15th century

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More Definitions for killer



English Language Learners Definition of killer

 (Entry 1 of 2)

: a person or thing that kills someone or something
informal : something that is very difficult



English Language Learners Definition of killer (Entry 2 of 2)

chiefly US
: causing death or destruction
informal : very impressive or appealing
informal : very difficult


kill·​er | \ ˈki-lər How to pronounce killer (audio) \

Kids Definition of killer

 (Entry 1 of 2)

: someone or something that takes the life of a person or animal



Kids Definition of killer (Entry 2 of 2)

1 : very impressive or effective a killer smile
2 : very difficult a killer exam
3 : causing death or ruin a killer tornado

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More from Merriam-Webster on killer

Rhyming Dictionary: Words that rhyme with killer

Thesaurus: All synonyms and antonyms for killer

Spanish Central: Translation of killer

Nglish: Translation of killer for Spanish Speakers

Britannica English: Translation of killer for Arabic Speakers

Comments on killer

What made you want to look up killer? Please tell us where you read or heard it (including the quote, if possible).


concealment of treason or felony

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