killer

1 of 2

noun

kill·​er ˈki-lər How to pronounce killer (audio)
Synonyms of killernext
1
: one that kills
2
: killer whale
3
a
: one that has a forceful, violent, or striking impact
b
: one that is extremely difficult to deal with

killer

2 of 2

adjective

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

Synonyms of killer

Relevance

Noun

Adjective

See All Synonyms & Antonyms in Thesaurus

Examples of killer in a Sentence

Noun Heart disease is the leading killer of both men and women. The chemical is used as a weed killer. Adjective killer viruses that claimed millions of lives a killer exercise program guaranteed to whip you into shape
Recent Examples on the Web
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.
Noun
Sure enough, Blauvelt's body was found in the basement of the Simpsonville house in a box covered in plywood, setting off a search for her killer that would last years. — ABC News, 9 Oct. 2026 Who could have guessed the industry that would spawn from this story of a boy who ends up playing with a doll that’s been cursed by the soul of a serial killer? — Brian Tallerico, Vulture, 9 Oct. 2026 Under Paris France, 2024 A female scientist battles a killer shark who turns up in the Seine. — Cynthia Littleton, Variety, 9 Oct. 2026 Monaghan previously represented serial killer Joseph Duncan, who murdered four members of a North Idaho family in 2005. — Idaho Statesman, 9 Oct. 2026 See All Example Sentences for killer

Word History

First Known Use

Noun

15th century, in the meaning defined at sense 1

Adjective

1939, in the meaning defined at sense 2

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

Phrases Containing killer

Rhymes for killer

See All Rhymes for killer

Browse Nearby Words

killefer
killer
killer app
See all Nearby Words

Cite this Entry

“Killer.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/killer. Accessed 14 Oct. 2026.

Copy Citation

Kids Definition

killer

1 of 2 noun
ˈkil-ər
1
: one that kills
2
: killer whale

killer

2 of 2 adjective
1
: strikingly impressive or effective
a killer smile
2
: extremely difficult
a killer exam
also : causing death or devastation
a killer tornado
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

Last Updated: - Updated example sentences

More from Merriam-Webster

Word of the Day

Listen to the pronunciation of deportment

See Definitions and Examples »

Popular in Grammar & Usage

See More

Do You Need a New Language Peeve?

The Exceptions of '-s' and '-es' Plurals

Merriam-Webster’s Great Big List of Words You Love to Hate

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

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

Popular in Wordplay

See More

The Real Origin of 'Supercalifragilistic'

9 Words That Sound Like Insults But Aren't

7 Words for Bad Endings and Rough Situations

The Words of the Week - Oct. 9

Why do we call it a 'flea market'?
See More

Popular

See More

Do You Need a New Language Peeve?

The Real Origin of 'Supercalifragilistic'

9 Words That Sound Like Insults But Aren't
See More

Games & Quizzes

See All
Play Quordle: Guess all four words in a limited number of tries. Each of your guesses must be a real 5-letter word.
Quordle Can you solve 4 words at once?
Play Blossom: Solve today's spelling word game by finding as many words as you can using just 7 letters. Longer words score more points.
Blossom Pick the best words!
Play Missing Letter: a crossword with a twist. Each of the 25 puzzle words start with a different letter of the alphabet. Which letter is missing?
The Missing Letter A daily crossword with a twist
a cup of tea and a golf ball on tee side by side
Quiz: Sounds Like... Choose the word that sounds like it fits the clue...
See All