killer

1 of 2

noun

kill·​er ˈki-lər 

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

Noun

• headache
• job

Adjective

• lethal
• deadly
• fatal

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

Noun

Or the time a serial killer, who was actually Marlena under hypnosis, seemed to kill several beloved characters. — Lisa Boone, Los Angeles Times, 10 July 2026

Although the plot of the film is fictional, the character of Leatherface was inspired by the American grave robber and serial killer Ed Gein. — Jordana Rosenfeld, Encyclopedia Britannica, 10 July 2026

Prosecutors questioned law enforcement officers about the chaotic moments after Kirk, 31, was shot while speaking at Utah Valley University in September 2025, and the efforts to collect evidence and track down his killer. — N'dea Yancey-Bragg, USA Today, 10 July 2026

Geena Davis wasn’t the first big name that Barbara Holmes heard could play the serial killer who once owned her house. — Graham Womack, Sacbee.com, 9 July 2026

Word History

First Known Use

Noun

15th century, in the meaning defined at sense 1

Adjective

1939, in the meaning defined at sense 2

Phrases Containing killer

• killer app
• killer bee
• killer cell
• killer instinct
• killer T cell
• killer T lymphocyte
• killer whale
• lady-killer
• natural killer cell
• pain-killer
• time killer

Rhymes for killer

• biller
• chiller
• driller
• filler
• hilar
• hiller
• pillar
• quiller
• siller
• spiller
• stiller
• thriller

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