# killer

/ˈkɪɫɝ/ (US) · /kˈɪlɐ/ (UK)

Source: https://englishreference.com/word/killer
Updated: 2026-06-19

## Senses

### 1. one who kills

noun · CEFR A2

a person, animal, or thing that causes death.

For teachers: a person, animal, or agent that causes the death of another living being.

- The police are still searching for the killer after the attack.
- The documentary explores how the invasive species became a silent killer of the local bird population within just a few years.

### 2. something very difficult

noun · CEFR B2 · Informal

something that is extremely hard to do or causes a lot of stress.

For teachers: a task, situation, or experience that is exceptionally taxing or difficult to endure.

- That three-hour exam was a real killer.
- The final climb of the race is a absolute killer, forcing even the most seasoned cyclists to push their physical limits.

### 3. killer whale

noun · CEFR B1

another name for an orca.

For teachers: a common shorthand for the orca (Orcinus orca).

- We saw a pod of killer whales swimming near the boat.
- Marine biologists observed the killer whales using sophisticated hunting techniques to isolate their prey from the rest of the pod.

### 4. excellent or impressive

adjective · CEFR B2 · Slang

very impressive, effective, or cool.

For teachers: strikingly effective, impressive, or fashionable. Often used in marketing or casual praise.

- She gave a killer presentation that convinced the whole board.
- The startup's new app features a killer interface that sets it apart from every other competitor in the crowded fintech market.

### 5. causing death

adjective · CEFR B2

deadly or very dangerous.

For teachers: having the capacity or tendency to cause death or total destruction.

- The city was hit by a killer heatwave last summer.
- The researchers identified a killer strain of the virus that appeared resistant to conventional antibiotic treatments.

## Examples

- She has a killer serve that is impossible to return.
- The striker scored a killer goal in the final minute to win the championship.
- The team's killer instinct allowed them to capitalize on every minor defensive error made by their opponents during the second half.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.