killer

American  

[kil-er] / ˈkɪl ər /

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.

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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 British  

/ 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

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Usage

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.

Other Word Forms

• self-killer noun

Etymology

Origin of killer

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

Example Sentences

In fact, it specializes in “mid,” or “gourmet cheeseburger,” TV, shows that look sharp, have a great cast, a killer setup…yet still leave you wanting just a bit more.

From MarketWatch

Other hot games are 99 Nights in the Forest, in which players try to survive killer deer and Grow a Garden, which is exactly as it sounds.

From Barron's

Gino Cecchettin isn't sure such a law would have saved his daughter: her killer was sent to prison for life in any case.

From BBC

But although City monopolised possession, they lacked a killer instinct and paid for a sloppy piece of defending in the 23rd minute.

From Barron's

The internet wasn’t a huge job killer overall, but for some occupations, it wasn’t a gentle decline—it was a cliff.

From The Wall Street Journal