killer

[kil-er]

noun

1. a person or thing that kills. kill.

2. killer whale.

3. a device used by a post office for printing cancellations on postage stamps.

4. a mark of cancellation made on a postage stamp.

5. Slang.,  something or someone having a formidable impact, devastating effect, etc..

   The math test was a real killer.

adjective

Slang.

1. severe; powerful.

   a killer cold.

2. very difficult or demanding.

   a killer chess tournament.

3. highly effective; superior.

   a killer recipe for fried chicken.

killer

/ ˈkɪlə /

noun

1. 1. a person or animal that kills, esp habitually

   2. ( as modifier )

      a killer shark

2. something, esp a task or activity, that is particularly taxing or exhausting

3. an animal selected to be slaughtered for food

Other Word Forms

• self-killer noun

Word History and Origins

Origin of killer¹

First recorded in 1525–35; kill ¹ + -er ¹

Example Sentences

The project is costly and logistically difficult, and must contend with a Chinese arsenal that now features upgraded versions of the DF-26, a missile known as the “Guam killer.”

Read more on The Wall Street Journal

Sir David's killer, Ali Harbi Ali, is in prison for life.

Read more on BBC

The throbbing “On the Prowl” sounds at first like the story of a guy hitting the streets looking for a good time but upon closer listening seems more like a serial killer cruising for victims.

Read more on The Wall Street Journal

Students could still discuss the war in Gaza, but teachers couldn’t portray the Jewish state and its supporters as genocidal killers.

Read more on The Wall Street Journal

But a lot of these killings go uninvestigated and killers walk free.

Read more on The Wall Street Journal

When To Use

What is a basic definition of killer?

A killer is a person or thing that kills, meaning they end lives. Killer is also used in slang to mean something that is devastating or exhausting. Additionally, killer is used in slang to describe something as severe or powerful. Killer has several other meanings as a noun and an adjective.A person or thing that ends someone’s life is a killer. In terms of a person, killer is often used interchangeably with murderer. However, killer can refer to someone who killed another person by accident, while murderer is not used in that sense.

• Real-life examples: John Wilkes Booth was Abraham Lincoln’s killer. Jack the Ripper was an infamous killer. Bacteria and viruses often act as natural killers. People use weed killers on their lawns.



• Used in a sentence: My cat is a very effective killer of birds.

In slang, killer is used to describe something as causing stress, exhaustion, pain, or misery.

• Real-life examples: You might call a particularly hard test a killer test. A killer workout would push your body to the limits of its abilities.



• Used in a sentence: That history assignment turned out to be a killer and took me forever to finish.

In slang, killer is also used to describe something as severe, intense, or powerful.

• Real-world examples: You might call a baseball game that goes into extra innings with a 2–2 score, a killer game. If you come down with a severe cold that keeps you in bed for several days, you could call it a killer cold.



• Used in a sentence: After living abroad for five years, Michelle came down with a killer case of homesickness.