knock
B1Neutral to informal
Definition
Meaning
To strike a surface with a sharp blow, typically to make a noise or gain attention.
To criticize or find fault with someone or something; to collide with something; to reduce a price or amount; to impress someone (slang).
Linguistics
Semantic Notes
The verb 'knock' often implies intention when referring to striking a door, but can imply accident when referring to collisions. The noun form refers to the sound or act of knocking.
Dialectal Variation
British vs American Usage
Differences
Minor differences in collocational frequency (e.g., 'knock up' has very different primary meanings). Spelling identical.
Connotations
In UK slang, 'knock' can mean to criticize harshly; in US, 'knock' as slang for impress ('It really knocks me out') is more established.
Frequency
Comparably frequent in both dialects.
Vocabulary
Collocations
Grammar
Valency Patterns
knock [on/at] somethingknock something [over/down/out]knock someone [out/cold]knock [into/against] somethingVocabulary
Synonyms
Strong
Neutral
Weak
Vocabulary
Antonyms
Phrases
Idioms & Phrases
- “knock on wood”
- “knock it off”
- “knock someone's socks off”
- “knock the wind out of someone's sails”
- “death knock”
Usage
Context Usage
Business
Used informally in phrases like 'knock down the price' or 'knock off work'.
Academic
Rare in formal academic writing except in specific technical contexts (e.g., engine knock).
Everyday
Very common for describing the action at a door, minor collisions, or informal criticism.
Technical
In engineering, refers to undesirable combustion in engines ('engine knock').
Examples
By Part of Speech
noun
British English
- There was a loud knock at the door around midnight.
- The engine has developed a worrying knock.
- He took a few knocks early in his career.
American English
- I heard a knock, but no one was there.
- A sharp knock came from the engine.
- She's a writer who can take a knock and keep going.
verb
British English
- Could you knock on the door before entering?
- I'm afraid I've knocked my knee on the table.
- He's always knocking the government's policies.
American English
- Please knock before you come in.
- She knocked over her coffee cup.
- That performance really knocked me out.
Examples
By CEFR Level
- Knock on the door and wait.
- I knocked the glass off the table by accident.
- Someone is knocking at the window.
- The news really knocked the confidence out of him.
- Critics have been quick to knock his latest film.
- We managed to knock £50 off the asking price.
- The new evidence could knock the prosecution's case for six.
- He has a reputation for knocking out a first draft in a weekend.
Learning
Memory Aids
Mnemonic
Imagine a clock (sounds like 'knock') on the wall – you knock on the wall to check if the clock is hanging straight.
Conceptual Metaphor
CRITICISM IS A PHYSICAL BLOW (e.g., 'He knocked my proposal').
Watch out
Common Pitfalls
Translation Traps (for Russian speakers)
- Не переводить 'knock on wood' дословно (используется 'тьфу-тьфу' или 'постучи по дереву' с пояснением).
- В значении 'сбить цену' – 'knock down the price', а не 'beat down the price'.
- 'Knock it off!' означает 'Прекрати!', а не 'Сбей это!'.
Common Mistakes
- Using 'knock the door' instead of 'knock on/at the door'.
- Confusing 'knock out' (make unconscious) with 'knock off' (stop work).
- Using 'knock' for a gentle touch – it implies a percussive sound.
Practice
Quiz
In the idiom 'knock it off', what does 'knock' mean?
FAQ
Frequently Asked Questions
The standard prepositional phrase is 'knock on the door' (or 'knock at the door'). 'Knock the door' is generally considered incorrect or dialectal.
'Knock down' often implies bringing something to the ground, often from an upright position (knock down a wall). 'Knock over' often implies causing something to fall or spill, especially a contained object (knock over a glass).
Yes, in informal slang, particularly American, 'knock out' can mean to greatly impress ('That song really knocks me out'). Also, 'knock' can mean to achieve something quickly ('knock out an essay').
It's a technical term for a pinging or knocking sound in an internal combustion engine caused by premature ignition of the fuel-air mixture, which is inefficient and damaging.