# knock

/ˈnɑk/ (US) · /nˈɒk/ (UK)

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

## Senses

### 1. to rap on a surface

verb · CEFR A2

to hit a surface with your knuckles or a hard object to make a sound, usually to get attention.

For teachers: to strike a surface, typically a door, with the knuckles or a knocker to signal one's presence or request entry.

- I had to knock on the door three times before anyone heard me.
- The courier had to knock repeatedly on the heavy oak door before the receptionist finally emerged from the back office.

Usage: Often used with the preposition 'on'.

### 2. to hit or bump

verb · CEFR B1

to hit something by accident, often causing it to move or fall.

For teachers: to strike or collide with something, often resulting in displacement or damage.

- Be careful not to knock that vase off the table with your bag.
- The cyclist was nearly knocked off his bike when a car door opened suddenly in his path.

Usage: Frequently used in phrasal verbs like 'knock over' or 'knock down'.

### 3. to criticize

verb · CEFR B2 · Informal

to say negative things about something or someone.

For teachers: to criticize or disparage something, often unfairly or habitually.

- Don't knock it until you've tried it; the food is actually quite good.
- Critics were quick to knock the director's latest film, though audiences seemed to appreciate its unconventional pacing.

### 4. a rapping sound

noun · CEFR A2

the sound made when someone hits a door or surface.

For teachers: the sound produced by a sharp blow or rap against a hard surface.

- There was a loud knock at the door just as we sat down for dinner.
- A sharp, rhythmic knock echoed through the hallway, startling the residents who were not expecting visitors so late.

### 5. a setback or blow

noun · CEFR B2 · Informal

a difficult experience or a failure that hurts your progress.

For teachers: a figurative blow, setback, or unfortunate experience that affects one's confidence or progress.

- Losing his job was a big knock to his confidence.
- The company took a serious knock when its main competitor released a cheaper, more efficient version of the same product.

### 6. engine noise

noun · CEFR C2 · Technical

a metallic sound in a car engine that shows something is wrong.

For teachers: a characteristic metallic sound in an internal combustion engine caused by improper combustion.

- The mechanic said the knock in the engine was caused by low-quality fuel.
- Persistent engine knock can lead to significant mechanical failure if the timing of the spark ignition is not adjusted immediately.

## Examples

- I heard a loud knock at the front door.
- Losing the first match was a real knock to the team's confidence.
- Despite the knock he took to his professional reputation during the scandal, he managed to rebuild his career through persistent community service and transparency.

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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.